Weather Weather is the state of the atmosphere, to the degree that it is hot or cold, wet or dry, calm or stormy, clear or cloudy. Most weather phenomena occur in the troposphere, just below the stratosphere. Weather generally refers to day-to-day temperature and precipitation activity, whereas climate is the term for the average atmospheric conditions over longer periods of time. When used without qualification, "weather" is understood to mean the weather of Earth. Weather is driven by air pressure (temperature and moisture) differences between one place and another. These pressure and temperature differences can occur due to the sun angle at any particular spot, which varies by latitude from the tropics. The strong temperature contrast between polar and tropical air gives rise to the jet stream. Weather systems in the mid-latitudes, such as extra tropical cyclones, are caused by instabilities of the jet stream flow. Because the Earth's axis is tilted relative to its orbital plane, sunlight is incident at different angles at different times of the year. On Earth's surface, temperatures usually range ±40 °C (−40 °F to 100 °F) annually. Over thousands of years, changes in Earth's orbit affect the amount and distribution of solar energy received by the Earth and influence long-term climate and global climate change. Surface temperature differences in turn cause pressure differences. Higher altitudes are cooler than lower altitudes due to differences in compressional heating. Weather forecasting is the application of science and technology to predict the state of the atmosphere for a future time and a given location. The atmosphere is a chaotic system, so small changes to one part of the system can grow to have large effects on the system as a whole. Human attempts to control the weather have occurred throughout human history, and there is evidence that human activity such as agriculture and industry has inadvertently modified weather patterns. Studying how the weather works on other planets has been helpful in understanding how weather works on Earth. A famous landmark in the Solar System, Jupiter's Great Red Spot, is an anticyclonic storm known to have existed for at least 300 years. However, weather is not limited to planetary bodies. A star's corona is constantly being lost to space, creating what is essentially a very thin atmosphere throughout the Solar System. The movement of mass ejected from the Sun is known as the solar wind. Cause On Earth, common weather phenomena include wind, cloud, rain, snow, fog and dust storms. Less common events include natural disasters such as tornadoes, hurricanes, typhoons and ice storms. Almost all familiar weather phenomena occur in the troposphere (the lower part of the atmosphere). Weather does occur in the stratosphere and can affect weather lower down in the troposphere, but the exact mechanisms are poorly understood. Weather occurs primarily due to air pressure (temperature and moisture) differences between one place to another. These differences can occur due to the sun angle at any particular spot, which varies by latitude from the tropics. In other words, the farther from the tropics one lies, the lower the sun angle is, which causes those locations to be cooler due to the indirect sunlight. The strong temperature contrast between polar and tropical air gives rise to the jet stream. Weather systems in the mid-latitudes, such as extratropical cyclones, are caused by instabilities of the jet stream flow. Weather systems in the tropics, such as monsoons or organized thunderstorm systems, are caused by different processes. Because the Earth's axis is tilted relative to its orbital plane, sunlight is incident at different angles at different times of the year. In June the Northern Hemisphere is tilted towards the sun, so at any given Northern Hemisphere latitude sunlight falls more directly on that spot than in December. This effect causes seasons. Over thousands to hundreds of thousands of years, changes in Earth's orbital parameters affect the amount and distribution of solar energy received by the Earth and influence long-term climate. The uneven solar heating (the formation of zones of temperature and moisture gradients, or frontogenesis) can also be due to the weather itself in the form of cloudiness and precipitation. Higher altitudes are cooler than lower altitudes, which is explained by the lapse rate. On local scales, temperature differences can occur because different surfaces (such as oceans, forests, ice sheets, or man-made objects) have differing physical characteristics such as reflectivity, roughness, or moisture content. Surface temperature differences in turn cause pressure differences. A hot surface heats the air above it and the air expands, lowering the air pressure and its density. The resulting horizontal pressure gradient accelerates the air from high to low pressure, creating wind, and Earth's rotation then causes curvature of the flow via the Coriolis Effect. The simple systems thus formed can then display emergent behavior to produce more complex systems and thus other weather phenomena. Large scale examples include the Hadley cell while a smaller scale example would be coastal breezes. The atmosphere is a chaotic system, so small changes to one part of the system can grow to have large effects on the system as a whole. This makes it difficult to accurately predict weather more than a few days in advance, though weather forecasters are continually working to extend this limit through the scientific study of weather, meteorology. It is theoretically impossible to make useful day-to-day predictions more than about two weeks ahead, imposing an upper limit to potential for improved prediction skill. Weathering Weather is one of the fundamental processes that shape the Earth. The process of weathering breaks down the rocks and soils into smaller fragments and then into their constituent substances. During rains precipitation, the water droplets absorb and dissolve carbon dioxide from the surrounding air. This causes the rainwater to be slightly acidic, which aids the erosive properties of water. The released sediment and chemicals are then free to take part in chemical reactions that can affect the surface further (such as acid rain), and sodium and chloride ions (salt) deposited in the seas/oceans. The sediment may reform in time and by geological forces into other rocks and soils. In this way, weather plays a major role in erosion of the surface. Effect on Humans Weather has played a large and sometimes direct part in human history. Aside from climatic changes that have caused the gradual drift of populations (for example the desertification of the Middle East, and the formation of land bridges during glacial periods), extreme weather events have caused smaller scale population movements and intruded directly in historical events. One such event is the saving of Japan from invasion by the Mongol fleet of Kublai Khan by the Kamikaze winds in 1281. French claims to Florida came to an end in 1565 when a hurricane destroyed the French fleet, allowing Spain to conquer Fort Caroline. More recently, Hurricane Katrina redistributed over one million people from the central Gulf coast elsewhere across the United States, becoming the largest diaspora in the history of the United States. The Little Ice Age caused crop failures and famines in Europe. The 1690s saw the worst famine in France since the Middle Ages. Finland suffered a severe famine in 1696–1697, during which about one-third of the Finnish population died. The human body is negatively affected by extremes in temperature, humidity, and wind. Weather Forecasting Weather forecasting is the application of science and technology to predict the state of the atmosphere for a future time and a given location. Human beings have attempted to predict the weather informally for millennia, and formally since at least the nineteenth century. Weather forecasts are made by collecting quantitative data about the current state of the atmosphere and using scientific understanding of atmospheric processes to project how the atmosphere will evolve. Once an all-human endeavor based mainly upon changes in barometric pressure, current weather conditions, and sky condition, forecast models are now used to determine future conditions. Human input is still required to pick the best possible forecast model to base the forecast upon, which involves pattern recognition skills, teleconnections, knowledge of model performance, and knowledge of model biases. The chaotic nature of the atmosphere, the massive computational power required to solve the equations that describe the atmosphere, error involved in measuring the initial conditions, and an incomplete understanding of atmospheric processes mean that forecasts become less accurate as the difference in current time and the time for which the forecast is being made increases. The use of ensembles and model consensus helps to narrow the error and pick the most likely outcome. There are a variety of end users to weather forecasts. Weather warnings are important forecasts because they are used to protect life and property. Forecasts based on temperature and precipitation are important to agriculture, and therefore to commodity traders within stock markets. Temperature forecasts are used by utility companies to estimate demand over coming days. On an everyday basis, people use weather forecasts to determine what to wear on a given day. Since outdoor activities are severely curtailed by heavy rain, snow and the wind chill, forecasts can be used to plan activities around these events, and to plan ahead and survive them. Weather Extremes On Earth, temperatures usually range ±40 °C (100 °F to −40 °F) annually. The range of climates and latitudes across the planet can offer extremes of temperature outside this range. The coldest air temperature ever recorded on Earth is −89.2 °C (−128.6 °F), at Vostok Station, Antarctica on 21 July 1983. The hottest air temperature ever recorded was 57.7 °C (135.9 °F) at Aziziya, Libya, on 13 September 1922, but that reading is queried. The highest recorded average annual temperature was 34.4 °C (93.9 °F) at Dallol, Ethiopia. The coldest recorded average annual temperature was −55.1 °C (−67.2 °F) at Vostok Station, Antarctica. The coldest average annual temperature in a permanently inhabited location is at Eureka, Nunavut, in Canada, where the annual average temperature is −19.7 °C (−3.5 °F). Space Weather Weather is not limited to planetary bodies. Like all stars, the sun's corona is constantly being lost to space, creating what is essentially a very thin atmosphere throughout the Solar System. The movement of mass ejected from the Sun is known as the solar wind. Inconsistencies in this wind and larger events on the surface of the star, such as coronal mass ejections, form a system that has features analogous to conventional weather systems (such as pressure and wind) and is generally known as space weather. Coronal mass ejections have been tracked as far out in the solar system as Saturn. The activity of this system can affect planetary atmospheres and occasionally surfaces. The interaction of the solar wind with the terrestrial atmosphere can produce spectacular aurora, and can play havoc with electrically sensitive systems such as electricity grids and radio signals. Climate Climate is a measure of the average pattern of variation in temperature, humidity, atmospheric pressure, wind, precipitation, atmospheric particle count and other meteorological variables in a given region over long periods of time. Climate is different than weather, in that weather only describes the short-term conditions of these variables in a given region. A region's climate is generated by the climate system, which has five components: atmosphere, hydrosphere, cryosphere, land surface, and biosphere. The climate of a location is affected by its latitude, terrain, and altitude, as well as nearby water bodies and their currents. Climates can be classified according to the average and the typical ranges of different variables, most commonly temperature and precipitation. The most commonly used classification scheme was originally developed by Wladimir Köppen. The Thornthwaite system, in use since 1948, incorporates evapotranspiration along with temperature and precipitation information and is used in studying animal species diversity and potential effects of climate changes. The Bergeron and Spatial Synoptic Classification systems focus on the origin of air masses that define the climate of a region. Paleoclimatology is the study of ancient climates. Since direct observations of climate are not available before the 19th century, paleoclimates are inferred from proxy variables that include non-biotic evidence such as sediments found in lake beds and ice cores, and biotic evidence such as tree rings and coral. Climate models are mathematical models of past, present and future climates. Climate change may occur over long and short timescales from a variety of factors; recent warming is discussed in global warming. Köppen Climate Classification The Köppen classification depends on average monthly values of temperature and precipitation. The most commonly used form of the Köppen classification has five primary types labeled A through E. These primary types are A, tropical; B, dry; C, mild mid-latitude; D, cold mid-latitude; and E, polar. The five primary classifications can be further divided into secondary classifications such as rain forest, monsoon, tropical savanna, humid subtropical, humid continental, oceanic climate, Mediterranean climate, steppe, subarctic climate, tundra, polar ice cap, and desert. Rain forests are characterized by high rainfall, with definitions setting minimum normal annual rainfall between 1,750 millimetres (69 in) and 2,000 millimetres (79 in). Mean monthly temperatures exceed 18 °C (64 °F) during all months of the year. A monsoon is a seasonal prevailing wind which lasts for several months, ushering in a region's rainy season. Regions within North America, South America, Sub-Saharan Africa, Australia and East Asia are monsoon regimes. A tropical savanna is a grassland biome located in semiarid to semi-humid climate regions of subtropical and tropical latitudes, with average temperatures remain at or above 18 °C (64 °F) year round and rainfall between 750 millimetres (30 in) and 1,270 millimetres (50 in) a year. They are widespread on Africa, and are found in India, the northern parts of South America, Malaysia, and Australia.[18] The humid subtropical climate zone where winter rainfall (and sometimes snowfall) is associated with large storms that the westerlies steer from west to east. Most summer rainfall occurs during thunderstorms and from occasional tropical cyclones. Humid subtropical climates lie on the east side continents, roughly between latitudes 20° and 40° degrees away from the equator. A humid continental climate is marked by variable weather patterns and a large seasonal temperature variance. Places with more than three months of average daily temperatures above 10 °C (50 °F) and a coldest month temperature below −3 °C (27 °F) and which do not meet the criteria for an arid or semiarid climate, are classified as continental. An oceanic climate is typically found along the west coasts at the middle latitudes of all the world's continents, and in southeastern Australia, and is accompanied by plentiful precipitation year round. The Mediterranean climate regime resembles the climate of the lands in the Mediterranean Basin, parts of western North America, parts of Western and South Australia, in southwestern South Africa and in parts of central Chile. The climate is characterized by hot, dry summers and cool, wet winters. A steppe is a dry grassland with an annual temperature range in the summer of up to 40 °C (104 °F) and during the winter down to −40 °C (−40 °F). A subarctic climate has little precipitation, and monthly temperatures which are above 10 °C (50 °F) for one to three months of the year, with permafrost in large parts of the area due to the cold winters. Winters within subarctic climates usually include up to six months of temperatures averaging below 0 °C (32 °F). Tundra occurs in the far Northern Hemisphere, north of the taiga belt, including vast areas of northern Russia and Canada. A polar ice cap, or polar ice sheet, is a high-latitude region of a planet or moon that is covered in ice. Ice caps form because high-latitude regions receive less energy as solar radiation from the sun than equatorial regions, resulting in lower surface temperatures. A desert is a landscape form or region that receives very little precipitation. Deserts usually have a large diurnal and seasonal temperature range, with high or low, depending on location daytime temperatures (in summer up to 45 °C or 113 °F), and low nighttime temperatures (in winter down to 0 °C or 32 °F) due to extremely low humidity. Many deserts are formed by rain shadows, as mountains block the path of moisture and precipitation to the desert. Climate Change Climate change is the variation in global or regional climates over time. It reflects changes in the variability or average state of the atmosphere over time scales ranging from decades to millions of years. These changes can be caused by processes internal to the Earth, external forces (e.g. variations in sunlight intensity) or, more recently, human activities. In recent usage, especially in the context of environmental policy, the term "climate change" often refers only to changes in modern climate, including the rise in average surface temperature known as global warming. In some cases, the term is also used with a presumption of human causation, as in the United Nations Framework Convention on Climate Change (UNFCCC). The UNFCCC uses "climate variability" for non-human caused variations. Earth has undergone periodic climate shifts in the past, including four major ice ages. These consisting of glacial periods where conditions are colder than normal, separated by interglacial periods. The accumulation of snow and ice during a glacial period increases the surface albedo, reflecting more of the Sun's energy into space and maintaining a lower atmospheric temperature. Increases in greenhouse gases, such as by volcanic activity, can increase the global temperature and produce an interglacial. Suggested causes of ice age periods include the positions of the continents, variations in the Earth's orbit, changes in the solar output, and volcanism. Clouds In meteorology, a cloud is a visible mass of liquid droplets or frozen crystals made of water or various chemicals suspended in the atmosphere above the surface of a planetary body. These suspended particles are also known as aerosols and are studied in the cloud physics branch of meteorology. Terrestrial cloud formation is the result of air in Earth's atmosphere becoming saturated due to either or both of two processes; cooling of the air and adding water vapor. With sufficient saturation, precipitation will fall to the surface; an exception is virga, which evaporates before reaching the surface. Clouds in the troposphere, the atmospheric layer closest to Earth's surface, have Latin names due to the universal adaptation of Luke Howard's nomenclature. It was introduced in December 1802 and became the basis of a modern international system that classifies these tropospheric aerosols into several physical forms or categories, then cross-classifies them into families of low, middle and high according to cloud-base altitude range above Earth's surface. Clouds with significant vertical extent are often considered a separate family. One physical form shows free-convective upward growth into low or vertical heaps of cumulus. Other forms appear as non-convective layered sheets like low stratus, and as limited-convective rolls or ripples as with stratocumulus. Both of these layered forms have middle- and high-family variants identified respectively by the prefixes alto- and cirro-. Thin fibrous wisps of cirrus are a physical form found only at high altitudes. In the case of clouds with vertical extent, prefixes are used whenever necessary to express variations or complexities in their physical structures. These include cumulo- for complex highly convective vertical nimbus storm clouds, and nimbo- for thick stratiform layers with sufficient vertical depth to produce moderate to heavy precipitation. This process of cross-classification produces ten basic genus-types or genera, most of which can be subdivided into species and varieties. Synoptic surface weather observations use code numbers to record and report any type of tropospheric cloud visible at scheduled observation times based on its height and physical appearance. While a majority of clouds form in Earth's troposphere, there are occasions when they can be observed at much higher altitudes in the stratosphere and mesosphere. Clouds that form above the troposphere have common names for their main types, but are sub-classified alpha-numerically rather than with the elaborate system of Latin names given to cloud types in the troposphere. These three main atmospheric layers that can produce clouds, along with the lowest part of the cloudless thermosphere, are collectively known as the homosphere. Above this lies the heterosphere (which includes the rest of the thermosphere and the exosphere) that marks the transition to outer space. Clouds have been observed on other planets and moons within the Solar System, but, due to their different temperature characteristics, they are composed of other substances such as methane, ammonia, and sulfuric acid. Classification Low Level Cloud - Base is usually below 6,500ft Cumulus - These clouds usually form at altitudes between 1,000 and 5,000ft, though often temperature rises after formation lead to an increase in cloud base height. These clouds are generally formed by air rising as a result of surface heating and may occasionally produce light showers. Stratus - Usually forms between the surface and 2,000ft, but cloud base can be up to 4,000ft. Thick stratus can produce considerable precipitation, particularly in hilly or coastal regions, though in some cases this precipitation may be falling from higher clouds such as nimbostratus. While thick stratus will obscure the sun or moon, they are clearly visible through thin stratus. Stratocumulus - This cloud often occurs at altitudes between 1,000 and 4,000ft, though sometimes may be higher. While not generally producing precipitation these clouds may produce drizzle, particularly in hilly or coastal areas, and may be thick enough to obscure the sun or moon. These clouds consist entirely of liquid drops and are often formed close to the top of the planetary boundary layer. Cumulonimbus - Cloud base is typically between 2,000 and 5,000ft, though in some cases this may be lower or higher. These clouds are formed when conditions are such that deep convection is able to develop, and may have a huge vertical extent particularly in the tropics, sometimes reaching the tropopause. These clouds produce heavy showers, thunderstorms and hail, often also producing squally winds. At lower levels these clouds consist of liquid drops, but as altitude increases the cloud progresses through mixed phase and fully glaciated conditions. A fully developed cumulonimbus cloud may have a classic anvil appearance as the upper levels of the cloud spread out on reaching the tropopause. These systems may produce a considerable amount of cirrus cloud as the anvil spreads out. Mid Level Clouds – Base is usually between 6,500ft and 20,000ft with some exceptions. Mid level clouds typically form at temperatures between 0 and –40C depending on altitude and season, so may consist of warm or supercooled droplets and ice particles. Altostratus - Cloud base ranges between 10,000 and 20,000ft. Thicker forms of these clouds often produce continuous light precipitation and hide the sun or moon, though thinner forms show the sun or moon with a ground glass appearance. Altocumulus - This type of cloud typically occurs between 6,500 and 20,000ft and is generally broken in appearance, though can occasionally produce precipitation and be thick enough to hide the sun or moon. Nimbostratus - Cloud base ranges from the surface to 10,000ft. These clouds always hide the sun or moon, and normally produce continuous precipitation which is often moderate to heavy. High Level Clouds – Base is usually above 20,000ft Cirrus - Base is typically between 20,000 and 40,000ft in the UK, and may be considerably higher in the tropics. Cirrus clouds do not produce precipitation which reaches the ground, though streaks of particles (known as fall streaks) are often observed below these clouds. Various halos and other optical effects may be produced by cirrus cloud. In some cases these clouds are also thick enough to hide the sun. Cirrus clouds typically form at temperatures below -40C and consist entirely of ice particles. Cirrostratus - A thin high level layer cloud, which often produce halos and through which the outline of the sun is generally visible. These clouds are often the first visible indication of an approaching weather front, and may progressively thicken to altostratus and then nimbostratus with lowering of cloud base as the front approaches. Cirrocumulus - Typically found in a similar altitude range to cirrus, these clouds do not produce precipitation and are usually more broken in appearance than cirrus, with the position of the sun or moon being visible. Air Mass and Air Mass Boundaries In meteorology, an air mass is a volume of air defined by its temperature and water vapor content. Air masses cover many hundreds or thousands of square miles, and adopt the characteristics of the surface below them. They are classified according to latitude and their continental or maritime source regions. Colder air masses are termed polar or arctic, while warmer air masses are deemed tropical. Continental and superior air masses are dry while maritime and monsoon air masses are moist. Weather fronts separate air masses with different density (temperature and/or moisture) characteristics. Once an air mass moves away from its source region, underlying vegetation and water bodies can quickly modify its character. Classification schemes tackle an air mass' characteristics, and well as modification. Classification The Bergeron classification is the most widely accepted form of air mass classification, though others have produced more refined versions of this scheme over different regions of the globe. Air mass classification involves three letters. The first letter describes its moisture properties, with c used for continental air masses (dry) and m for maritime air masses (moist). The second letter describes the thermal characteristic of its source region: T for Tropical, P for Polar, A for arctic or Antarctic, M for monsoon, E for Equatorial, and S for superior air (an adiabatically drying and warming air formed by significant downward motion in the atmosphere). The third letter is used to designate the stability of the atmosphere. If the air mass is colder than the ground below it, it is labeled k. If the air mass is warmer than the ground below it, it is labeled w. For instance, an air mass originating over the desert southwest of the United States in summer may be designated "cT". An air mass originating over northern Siberia in winter may be indicated as "cA". The stability of an air mass may be shown using a third letter, either "k" (air mass colder than the surface below it) or "w" (air mass warmer than the surface below it). An example of this might be a polar air mass blowing over the Gulf Stream, denoted as "cPk". Occasionally, one may also encounter the use of an apostrophe or "degree tick" denoting that a given air mass having the same notation as another it is replacing is colder than the replaced air mass (usually for polar air masses). For example, a series of fronts over the Pacific might show an air mass denoted mPk followed by another denoted mPk'. Another convention utilizing these symbols is the indication of modification or transformation of one type to another. For instance, an Arctic air mass blowing out over the Gulf of Alaska may be shown as "cA-mPk". Yet another convention indicates the layering of air masses in certain situations. For instance, the overrunning of a polar air mass by an air mass from the Gulf of Mexico over the Central United States might be shown with the notation "mT/cP" (sometimes using a horizontal line as in fraction notation). Characteristics Arctic, Antarctic, and polar air masses are cold. The qualities of arctic air are developed over ice and snow-covered ground. Arctic air is deeply cold, colder than polar air masses. Arctic air can be shallow in the summer, and rapidly modify as it moves equatorward. Polar air masses develop over higher latitudes over the land or ocean, are very stable, and generally shallower than arctic air. Polar air over the ocean (maritime) loses its stability as it gains moisture over warmer ocean waters. Tropical and equatorial air masses are hot as they develop over lower latitudes. Those that develop over land (continental) are drier and hotter than those that develop over oceans, and travel northward on the western periphery of the subtropical ridge. Maritime tropical air masses are sometimes referred to as trade air masses. Monsoon air masses are moist and unstable. Superior air masses are dry, and rarely reach the ground. It normally resides over maritime tropical air masses, forming a warmer and drier layer over the more moderate moist air mass below, forming what is known as a trade wind inversion over the maritime tropical air mass. Continental Polar air masses (cP) are air masses that are cold and dry due to their continental source region. Continental polar air masses that affect North America form over interior Canada. A Continental Tropical Air Mass is a type of tropical air produced over subtropical arid regions; it is hot and very dry. Movement and Fronts A weather front is a boundary separating two masses of air of different densities, and is the principal cause of meteorological phenomena. In surface weather analyses, fronts are depicted using various colored lines and symbols, depending on the type of front. The air masses separated by a front usually differ in temperature and humidity. Cold fronts may feature narrow bands of thunderstorms and severe weather, and may on occasion be preceded by squall lines or dry lines. Warm fronts are usually preceded by stratiform precipitation and fog. The weather usually clears quickly after a front's passage. Some fronts produce no precipitation and little cloudiness, although there is invariably a wind shift. Cold fronts and occluded fronts generally move from west to east, while warm fronts move poleward. Because of the greater density of air in their wake, cold fronts and cold occlusions move faster than warm fronts and warm occlusions. Mountains and warm bodies of water can slow the movement of fronts. When a front becomes stationary, and the density contrast across the frontal boundary vanishes, the front can degenerate into a line which separates regions of differing wind velocity, known as a shearline. This is most common over the open ocean. Weather Front Types Cold Front - is located at the leading edge of the temperature drop off, which in an isotherm analysis shows up as the leading edge of the isotherm gradient, and it normally lies within a sharp surface trough. Cold fronts often bring heavy thunderstorms, rain and hail. Cold fronts can produce sharper changes in weather and move up to twice as quickly as warm fronts, since cold air is denser than warm air and rapidly replaces the warm air preceding the boundary. Warm Front - are at the leading edge of a homogeneous warm air mass, which is located on the equatorward edge of the gradient in isotherms, and lie within broader troughs of low pressure than cold fronts. A warm front moves more slowly than the cold front which usually follows because cold air is denser and harder to remove from the Earth's surface. Occluded Front - is formed when a cold front overtakes a warm front and usually form around mature low-pressure areas. The cold and warm fronts curve naturally poleward into the point of occlusion, which is also known as the triple point. It lies within a sharp trough, but the air mass behind the boundary can be either warm or cold. Stationary Front - is a non-moving (or stalled) boundary between two air masses, neither of which is strong enough to replace the other. They tend to remain essentially in the same area for extended periods of time, usually moving in waves. There is normally a broad temperature gradient behind the boundary with more widely spaced isotherm packing. Storm A storm is any disturbed state of an astronomical body's atmosphere especially affecting its surface, and strongly implying severe weather. It may be marked by strong wind, hail, thunder and/or lightning (a thunderstorm), heavy precipitation (snowstorm, rainstorm), heavy freezing rain (ice storm), strong winds (tropical cyclone, windstorm), or wind transporting some substance through the atmosphere as in a dust storm, blizzard, sandstorm, etc. Storms generally lead to negative impacts to lives and property such as storm surge, heavy rain or snow (causing flooding or road impassibility), lightning, wildfires, and vertical wind shear; however, systems with significant rainfall can alleviate drought in places they move through. Heavy snowfall can allow special recreational activities to take place which would not be possible otherwise, such as skiing and snowmobiling. Storms are created when a center of low pressure develops with a system of high pressure surrounding it. This combination of opposing forces can create winds and result in the formation of storm clouds, such as the cumulonimbus. Small localized areas of low pressure can form from hot air rising off hot ground; resulting in smaller disturbances such as dust devils and whirlwinds. Types of Storms Ice Storm - are one of the most dangerous forms of winter storms. When surface temperatures are below freezing, but a thick layer of above freezing air remains aloft above ground level, rain can fall into the freezing layer and freeze upon impact into a glaze which is known as Freezing Rain. Blizzard - There are varying definitions for blizzards, both over time and by location. In general, a blizzard is accompanied by gale-force winds, heavy snow (accumulating at a rate of at least 5 centimeters (2 in) per hour), and very cold conditions (below approximately -10 degrees Celsius or 14 F). Snow Storm - A heavy fall of snow accumulating at a rate of more than 5 centimeters (2 in) per hour that lasts several hours. Snow storms, especially ones with a high liquid equivalent and breezy conditions, can down tree limbs, cut off power, and paralyze travel over a large region. Ocean Storm - Storm conditions out at sea are defined as having sustained winds of 48 knots (55 mph or 90 km/h) or greater. Usually just referred to as a storm, these systems can sink vessels of all types and sizes. Firestorm - are conflagrations which attain such intensity that they create and sustain their own wind systems. It is most commonly a natural phenomenon, created during some of the largest bushfires, forest fires, and wildfires. Dust Devil - a small, localized updraft of rising air. Wind Storm - A storm marked by high wind with little or no precipitation. Windstorm damage often opens the door for massive amounts of water and debris to cause further damage to a structure. Squall - sudden onset of wind increase of at least 16 knots (30 km/h) or greater sustained for at least one minute. Gale - An extratropical storm with sustained winds between 34-48 knots (39-55 mph or 63–90 km/h). Thunderstorm - is a type of storm that generates lightning and the attendant thunder. It is normally accompanied by heavy precipitation. Thunderstorms occur throughout the world, with the highest frequency in tropical rainforest regions where there are conditions of high humidity and temperature along with atmospheric instability. Tropical Cyclone - is a storm system with a closed circulation around a centre of low pressure, fueled by the heat released when moist air rises and condenses. The name underscores its origin in the tropics and their cyclonic nature. Hailstorm - a type of storm that precipitates round chunks of ice. Hailstorms usually occur during regular thunder storms. Tornado - is a violent, destructive wind storm occurring on land. Usually its appearance is that of a dark, funnel-shaped cyclone. Typhoon A typhoon is a mature tropical cyclone that develops in the western part of the North Pacific Ocean between 180° and 100°E. This region is referred to as the northwest Pacific basin. For organizational purposes, the northern Pacific Ocean is divided into three regions: the eastern (North America to 140°W), central (140°W to 180°), and western (180° to 100°E). The Regional Specialized Meteorological Center (RSMC) for tropical cyclone forecasts is in Japan, with other tropical cyclone warning centers for the northwest Pacific in Honolulu (the Joint Typhoon Warning Center), the Philippines and Hong Kong. While the RSMC names each system, the main name list itself is coordinated amongst 18 countries that have territories threatened by typhoons each year. The Philippines use their own naming list for systems which approach the country. Within the northwestern Pacific there are no official typhoon seasons as tropical cyclones form throughout the year. Like any tropical cyclone, there are six main requirements for typhoon formation and development: sufficiently warm sea surface temperatures, atmospheric instability, high humidity in the lower to middle levels of the troposphere, enough Coriolis force to develop a low pressure center, a pre-existing low level focus or disturbance, and low vertical wind shear. The majority of storms form between June and November whilst tropical cyclone formation is at a minimum between December and May. On average, the northwestern Pacific features the most numerous and intense tropical cyclones globally. Like other basins, they are steered by the subtropical ridge towards the west or northwest, with some systems recurving near and east of Japan. The Philippines receive a brunt of the landfalls, with China and Japan being impacted slightly less. Some of the deadliest typhoons in history have struck China. Southern China has the longest record of typhoon impacts for the region, with a thousand year sample via documents within their archives. Taiwan has received the wettest known typhoon on record for the northwest Pacific tropical cyclone basin. Frequency Nearly one-third of the world's tropical cyclones form within the western Pacific. This makes this basin the most active on Earth. Pacific typhoons have formed year round, with peak months from August to October. The peak months correspond to that of the Atlantic hurricane seasons. Along with a high storm frequency, this basin also features the most globally intense storms on record. One of the most recent busy seasons was 2004. Tropical cyclones form in any month of the year across the northwest Pacific Ocean, and concentrate around June and November in the northern Indian Ocean. The area just northeast of the Philippines is the most active place on Earth for tropical cyclones to exist. Across the Philippines themselves, activity reaches a minimum in February, before increasing steadily through June, and spiking from July through October, with September being the most active month for tropical cyclones across the archipelago. Activity falls off significantly in November. The most frequently impacted areas of the Philippines by tropical cyclones are northern and central Luzon and eastern Visayas. A ten-year average of satellite determined precipitation showed that at least 30 percent of the annual rainfall in the northern Philippines could be traced to tropical cyclones, while the southern islands receive less than 10 percent of their annual rainfall from tropical cyclones. Categories Category 1 - The National Hurricane Center (NHC) uses the Saffir-Simpson Hurricane Scale to categorize the severity of a typhoon (hurricane). According to this scale, when wind sustains a speed of 74 to 95 miles per hour, it is considered a category one typhoon. At this stage, dangerous winds and some threat of damage are expected. Mobile homes built before 1994 are particularly vulnerable. During a category one typhoon, winds can snap large branches from trees and uproot some small trees. Category 2 - A category two storm is classified by winds of 96 to 110 miles per hour. A category two storm is extremely dangerous, and extensive damages will likely be sustained. Frame homes that are poorly constructed are at risk for having their roofs blown off, and even well-constructed homes may suffer damage to roofing and siding. During a category two storm, the systems that filter water can become compromised and potable water may be scarce. Category 3 - Sustained winds of 111 to 130 miles per hour are expected during a category three typhoon. NHC predicts that "devastating damage will occur" during a category three storm including "a high percentage of roof covering and siding damage to apartment buildings and industrial buildings." The windows of high-rise buildings may be broken, and falling glass can remain a threat for many days after the typhoon has passed. Expect electricity to be off during and after a category three storm. Uprooted trees, sign posts and other debris can block roadways and prevent evacuation. Category 4 - Sustained winds of 131 to 155 miles per hour accompany a category four typhoon. During this level of storm, catastrophic damage should be expected. Most unsecured windows will likely be broken, and a large amount of structural damage to multi-level buildings will likely occur. It may take months to restore power and other services to a community after a category four typhoon. Category 5 - A category five typhoon also threatens catastrophic damage. A typhoon is considered category five when winds sustain speeds of 131 to 155 miles per hour. Complete destruction of some metal buildings and masonry walls is likely to occur during a category five storm. A community that is struck by this category of typhoon can expect food and water shortages, as well as power outages that may last for months. It can take months or even years to rebuild a community after a category five typhoon. Earthquake An earthquake (also known as a quake, tremor or temblor) is the result of a sudden release of energy in the Earth's crust that creates seismic waves. The seismicity, seismism or seismic activity of an area refers to the frequency, type and size of earthquakes experienced over a period of time. Earthquakes are measured using observations from seismometers. The moment magnitude is the most common scale on which earthquakes larger than approximately 5 are reported for the entire globe. The more numerous earthquakes smaller than magnitude 5 reported by national seismological observatories are measured mostly on the local magnitude scale, also referred to as the Richter scale. These two scales are numerically similar over their range of validity. Magnitude 3 or lower earthquakes are mostly almost imperceptible or weak and magnitude 7 and over potentially cause serious damage over larger areas, depending on their depth. The largest earthquakes in historic times have been of magnitude slightly over 9, although there is no limit to the possible magnitude. The most recent large earthquake of magnitude 9.0 or larger was a 9.0 magnitude earthquake in Japan in 2011, and it was the largest Japanese earthquake since records began. Intensity of shaking is measured on the modified Mercalli scale. The shallower an earthquake, the more damage to structures it causes, all else being equal. At the Earth's surface, earthquakes manifest themselves by shaking and sometimes displacement of the ground. When the epicenter of a large earthquake is located offshore, the seabed may be displaced sufficiently to cause a tsunami. Earthquakes can also trigger landslides, and occasionally volcanic activity. In its most general sense, the word earthquake is used to describe any seismic event, whether natural or caused by humans, that generates seismic waves. Earthquakes are caused mostly by rupture of geological faults, but also by other events such as volcanic activity, landslides, mine blasts, and nuclear tests. An earthquake's point of initial rupture is called its focus or hypocenter. The epicenter is the point at ground level directly above the hypocenter. Measurement of Intensity and Extent of Damage The intensity of an earthquake becomes weaker outward from the epicenter. However, various types of ground respond differently to earthquake vibrations. Buildings on filled ground are damaged more than structures built on solid rock even though both may be at the same distance from the epicenter. The magnitude of a particular earthquake is a single number which does not vary from place to place. Magnitude is the total energy released by an earthquake at its focus. Earthquakes of large magnitude are stronger and generally more destructive than those of small magnitude. The amount of destruction depends not only on the magnitude but on the kind of ground and types of buildings thereon, and on the location of the focus in relation to heavily populated areas. Large earthquakes are preceded by many aftershocks, which may persist for days or weeks. The first shock is the most damaging. However, sometimes an aftershock may be even more powerful than the original shock. The intensity of an earthquake is measured in terms of its geological effects and the overall damage it brings. There are two major scales in which earthquakes are measured. These two scales are the Mercalli Scale and the Richter Scale. Mercalli Scale The Mercalli scale was introduced at the turn of the 20th century by the Italian seismologist Giuseppe Mercalli. This scale measures the intensity of shaking with numbers from I to XII. Intensity I on this scale is defined as an event felt by very few people, whereas intensity XII is assigned to a catastrophic event that causes total destruction. Events of intensities II to III are roughly equivalent to quakes of magnitude 3 to 4 on the Richter scale, and XI to XII on the Mercalli scale correspond with magnitudes 8 to 9 on the Richter scale. I. Hardly felt II. Felt only by a few persons at rest, especially on upper floors of buildings. III. Can be felt by persons indoors, especially on upper floors of buildings. Many people do not recognize it as an earthquake. IV. Felt indoors by many, outdoors by few during the day. At night, some awakened. Dishes, windows, doors disturbed. Standing motor cars rocked noticeably. V. Felt by nearly everyone; many awakened. Some dishes, windows broken. Unstable objects overturned. VI. Felt by all VII. Considerable damage in poorly built or badly designed structures. VIII. Damage slight in specially designed structures. Damage great in poorly built structures. Heavy furniture overturned. IX. Damage considerable in specially designed structures. Damage great in substantial buildings, with partial collapse. Buildings shifted off foundations. X. Many objects destroyed, buildings collapse. XI. Few structures remain standing. Bridges destroyed. Rails bent greatly. XII. Total Damage. Richter Scale The Richter scale was named after the American seismologist Charles Francis Richter. This scale measures the motion of the land surface 60 mi from the epicenter, or focus, of the earthquake. An estimated 800 quakes of magnitudes 5 to 6 occur worldwide each year. About 50,000 quakes of magnitudes 3 to 4 occur each year, and only about one of magnitude 8 to 9 each year. Between to 0-4.3 on the Richter scale, People at rest upstairs notice shaking. Shaking felt indoors; hanging objects swing. Between 4.3-4.8 Sleeping people are awakened. Dishes, doors and trees shake and rock. Between 4.8-6.2 Difficult to stand; people walk unsteadily. Windows break; plaster, bricks, and tiles fall. Between 6.2-7.3 General panic. Damage to foundations; buildings destoyed. Water thrown out of river. Between 7.3-8.9 Total destruction; roads break up, rocks fall. Large cracks appear in ground. Climate of the Philippines The Climate of the Philippines is either tropical rainforest, tropical savanna or tropical monsoon, or humid subtropical (in higher-altitude areas) characterized by relatively high temperature, oppressive humidity and plenty of rainfall. There are two seasons in the country, the wet season and the dry season, based upon the amount of rainfall. This is dependent as well on your location in the country as some areas experience rain all throughout the year. Based on temperature, the seven warmest months of the year are from March to October; the winter monsoon brings cooler air from November to February. May is the warmest month, and January, the coolest. Weather in the Philippines is monitored and managed by the Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA). Rainfall The summer monsoon brings heavy rains to most of the archipelago from May to October. Annual average rainfall ranges from as much as 5,000 millimetres (196.9 in) in the mountainous east coast section of the country, to less than 1,000 millimetres (39.4 in) in some of the sheltered valleys. Monsoon rains, although hard and drenching, are not normally associated with high winds and waves. Rainfall usually happen mostly from the month of March to October. At least 30 percent of the annual rainfall in the northern Philippines can be traced to tropical cyclones, while the southern islands receiving less than 10 percent of their annual rainfall from tropical cyclones. The wettest known tropical cyclone to impact the archipelago was the July 1911 cyclone, which dropped over 1,168 millimetres (46.0 in) of rainfall within a 24-hour period in Baguio City. Temperature The average year-round temperature measured from all the weather stations in the Philippines, except Baguio City, is 26.6 °C (79.9 °F). Cooler days are usually felt in the month of January with temperature averaging at 25.5 °C (77.9 °F) and the warmest days, in the month of May with a mean of 28.3 °C (82.9 °F). Elevation factors significantly in the variation of temperature in the Philippines. In Baguio City, with an elevation of 1,500 m (5,000 ft) above sea level, the mean average is 18.3 °C (64.9 °F) or cooler by about 4.3 °C (15 °F). In 1915, a one-year study was conducted by William H. Brown of the Philippine Journal of Science on top of Mount Banahaw at 2,100 m. (6,900 ft) elevation. The mean temperature measured was 18.6 °C (65.5 °F), a difference of 10 °C (21.6 °F) from the lowland mean temperature. Climate Types Type I - Two pronounced season: dry from November to April and wet during the rest of the year. Type II - No dry season with a pronounced rainfall from November to January. Type III - Seasons are not very pronounced, relatively dry from November to April, and wet during the rest of the year. Type IV - Rainfall is more or less evenly distributed throughout the year. Typhoons in the Philippines The Philippines sit astride the typhoon belt, and the country suffers an annual onslaught of dangerous storms from July through October. These are especially hazardous for northern and eastern Luzon and the Bicol and Eastern Visayas regions, but Manila gets devastated periodically as well. Bagyó is the local term to any tropical cyclone in the Philippine Islands. From the statistics gathered by PAGASA from 1948 to 2004, around an average of 20 storms and/or typhoons per year enter the PAR (Philippine Area of Responsibility) - the designated area assigned to PAGASA to monitor during weather disturbances. Those that made landfall or crossed the Philippines, the average was nine per year. In 1993, a record 19 typhoons made landfall in the country making it the most in one year. The least amount per year were 4 during the years 1955, 1958, 1992 and 1997. PAGASA categorizes typhoons into four types according to wind speed. Once a tropical cyclone enters the Philippine Area of Responsibility, regardless of strength, PAGASA gives it a local name for identification purposes by the media, government, and the general public. Tropical Depressions have maximum sustained winds of between 55 kilometres per hour (30 kn) and 64 kilometres per hour (35 kn) near its center. Tropical Storms have maximum sustained winds of 65 kilometres per hour (35 kn) and 119 kilometres per hour (64 kn). Typhoons achieve maximum sustained winds of 120 kilometres per hour (65 kn) to 185 kilometres per hour (100 kn). Test 1. It is the state of the atmosphere, to the degree that it is hot or cold, wet or dry, calm or stormy, clear or cloudy. a. Climate b. Weather c. Weathering d. Season 2. It is a measure of the average pattern of variation in temperature, humidity, atmospheric pressure, wind, precipitation, atmospheric particle count and other meteorological variables in a given region over long periods of time. a. Climate b. Weather c. Weathering d. Season 3. The process of ___________ breaks down the rocks and soils into smaller fragments and then into their constituent substances. a. Climate b. Weather c. Weathering d. Season 4. A famous landmark in the Solar System, Jupiter's Great Red Spot, is an anticyclonic storm known to have existed for at least how many years? a. 30 b. 300 c. 3,000 d. 30,000 5. It is the movement of mass ejected from the Sun. a. Solar System b. Solar Sun c. Solar Star d. Solar Wind 6. Weather ___________ is the application of science and technology to predict the state of the atmosphere for a future time and a given location. a. Forecasting b. Predicting c. Counting d. Solving 7. It is the coldest air temperature ever recorded on Earth at Vostok Station, Antarctica on 21 July 1983. a. −100 °C b. −99.2 °C c. −89.2 °C d. −69.2 °C 8. The hottest air temperature ever recorded at Aziziya, Libya, on 13 September 1922. a. 37.7 °C b. 47.7 °C c. 57.7 °C d. 67.7 °C 9. It is a component of a region’s climate generated by the climate system. a. atmosphere b. hydrosphere c. biosphere d. All of the above 10. It is the study of ancient climates. a. Paleoclimatology b. Paleontology c. Paleolithics d. None of the above 11. It is characterized by high rainfall, with definitions setting minimum normal annual rainfall between 1,750 millimetres (69 in) and 2,000 millimetres (79 in). a. Rain Forest b. Monsoon c. Tropical Savanna d. Steppe 12. It is a dry grassland with an annual temperature range in the summer of up to 40 °C (104 °F) and during the winter down to −40 °C (−40 °F). a. Rain Forest b. Monsoon c. Tropical Savanna d. Steppe 13. It is a seasonal prevailing wind which lasts for several months, ushering in a region's rainy season. a. Rain Forest b. Monsoon c. Tropical Savanna d. Steppe 14. It occurs in the far Northern Hemisphere, north of the taiga belt, including vast areas of northern Russia and Canada. a. Tundra b. Ice Cap c. Desert d. None of the above 15. It is a visible mass of liquid droplets or frozen crystals made of water or various chemicals suspended in the atmosphere above the surface of a planetary body. a. Ice b. Snow c. Cloud d. Frost 16. Classification of clouds whose base is usually below 6,500ft. a. Low Level b. Mid Level c. High Level d. All of the above 17. These clouds usually form at altitudes between 1,000 and 5,000ft, though often temperature rises after formation lead to an increase in cloud base height. a. Cumulus b. Stratus c. Cirrus d. Nimbus 18. Usually forms between the surface and 2,000ft, but cloud base can be up to 4,000ft. a. Cumulus b. Stratus c. Cirrus d. Nimbus 19. Base is typically between 20,000 and 40,000ft in the UK, and may be considerably higher in the tropics. a. Cumulus b. Stratus c. Cirrus d. Nimbus 20. This type of cloud typically occurs between 6,500 and 20,000ft and is generally broken in appearance, though can occasionally produce precipitation and be thick enough to hide the sun or moon. a. Altocirrus b. Altocumulus c. Altonimbus d. All of the above 21. It is a volume of air defined by its temperature and water vapor content. a. Air Volume b. Air Mass c. Air Weight d. Air Density 22. It is located at the leading edge of the temperature drop off, which in an isotherm analysis shows up as the leading edge of the isotherm gradient, and it normally lies within a sharp surface trough. a. Cold Front b. Warm Front c. Occluded Front d. Stationary Front 23. It is a non-moving (or stalled) boundary between two air masses, neither of which is strong enough to replace the other. a. Cold Front b. Warm Front c. Occluded Front d. Stationary Front 24. It is formed when a cold front overtakes a warm front and usually form around mature low-pressure areas. a. Cold Front b. Warm Front c. Occluded Front d. Stationary Front 25. It moves more slowly than the cold front which usually follows because cold air is denser and harder to remove from the Earth's surface. a. Cold Front b. Warm Front c. Occluded Front d. Stationary Front 26. A ___________ is any disturbed state of an astronomical body's atmosphere especially affecting its surface, and strongly implying severe weather. a. Storm b. Hurricane c. Typhoon d. Tsunami 27. It is accompanied by gale-force winds, heavy snow (accumulating at a rate of at least 5 centimeters (2 in) per hour), and very cold conditions (below approximately -10 degrees Celsius or 14 F). a. Ice Storm b. Thunder Storm c. Blizzard d. Ocean Storm 28. It is considered as one of the most dangerous forms of winter storms. a. Ice Storm b. Thunder Storm c. Blizzard d. Ocean Storm 29. Usually just referred to as a storm, these systems can sink vessels of all types and sizes. a. Ice Storm b. Thunder Storm c. Blizzard d. Ocean Storm 30. It is a type of storm that generates lightning and the attendant thunder and is normally accompanied by heavy precipitation. a. Ice Storm b. Thunder Storm c. Blizzard d. Ocean Storm 31. An extratropical storm with sustained winds between 34-48 knots (39-55 mph or 63–90 km/h). a. Squall b. Gale c. Hailstorm d. Tornado 32. It is a violent, destructive wind storm occurring on land. Usually its appearance is that of a dark, funnel-shaped cyclone. a. Squall b. Gale c. Hailstorm d. Tornado 33. Sudden onset of wind increase of at least 16 knots (30 km/h) or greater sustained for at least one minute. a. Squall b. Gale c. Hailstorm d. Tornado 34. These are conflagrations which attain such intensity that they create and sustain their own wind systems. a. Firestorm b. Dust Devil c. Cyclone d. None of the above 35. A ___________is a mature tropical cyclone that develops in the western part of the North Pacific Ocean between 180° and 100°E. a. Hurricane b. Typhoon c. Storm d. Tsunami 36. Typhoons are located and usually develops in what ocean? a. Pacific b. Atlantic c. Indian d. All of the above 37. A storm classified by winds of 96 to 110 miles per hour. It is extremely dangerous, and extensive damages will likely be sustained. a. Category 1 b. Category 2 c. Category 3 d. Category 4 38. During this storm, most unsecured windows will likely be broken, and a large amount of structural damage to multi-level buildings will likely occur. a. Category 1 b. Category 2 c. Category 3 d. Category 4 39. During a category _____ typhoon, winds can snap large branches from trees and uproot some small trees. a. Category 1 b. Category 2 c. Category 3 d. Category 4 40. A ___________ is the result of a sudden release of energy in the Earth's crust that creates seismic waves. a. Earthquake b. Tremor c. Temblor d. All of the above 41. An earthquake's point of initial rupture is called its ___________. a. Point b. Center c. Focus d. Fault 42. The ___________ is the point at ground level directly above the hypocenter. a. Hypercenter b. Mesocenter c. Epicenter d. All of the above 43. Using the Mercalli Scale this intensity is felt indoors by many, outdoors by few during the day. At night, some awakened. Dishes, windows, doors disturbed. Standing motor cars rocked noticeably. a. I b. IV c. VII d. X 44. Using the Mercalli Scale this intensity has few structures remaining standing, bridges destroyed, and rails bent greatly. a. IX b. X c. XI d. XII 45. Using the Richter Scale it characterizes difficulty to stand; people walk unsteadily, windows break, plaster, bricks, and tiles fall. a. 0-4.3 b. 4.3-4.8 c. 4.8-6.2 d. 6.2-7.3 46. Using the Richter Scale it is characterized by sleeping people that are awakened; Dishes, doors and trees shake and rock. a. 0-4.3 b. 4.3-4.8 c. 4.8-6.2 d. 6.2-7.3 47. A climate type in the Philippines where there’s no dry season with a pronounced rainfall from November to January. a. Type I b. Type II c. Type III d. Type IV 48. A climate type in the Philippines where rainfall is more or less evenly distributed throughout the year. a. Type I b. Type II c. Type III d. Type IV 49. This administration monitors and manages weather in the Philippines. a. PAGASA b. PAGIBIG c. DILG d. NCR 50. It is the strongest typhoon ever recorded that hit the Philippines. a. Ondoy b. Yolanda c. Ruping d. Kadiang Answer Key 1. B 16. A 31. B 46. B 2. A 17. A 32. D 47. B 3. C 18. B 33. A 48. D 4. B 19. C 34. A 49. A 5. D 20. B 35. B 50. B 6. A 21. B 36. A 7. C 22. A 37. B References: www.weather.com 8. C 23. D 38. D www.theweathernetwork.com 9. D 24. C 39. A www.wikipedia.org 10. A 25. B 40. D library.thinkquest.org 11. A 26. A 41. C pagasa.dost.gov.ph 12. D 27. C 42. C 13. B 28. A 43. B Prepared by: Eduard Shannon G. Alvior, RN 14. A 29. D 44. C 15. C 30. B 45. C