Meteorology

Meteorology Weather = the condition of the atmospheric variables, such as temperature, air pressure, wind, and water vapor, at a particular location for a relatively short period of time.

Components of Weather What do you need to know today? There are many different causes of weather in the atmosphere. 2. Many different atmospheric processes affect New York State.

A. Earth’s Energy Energy from the SUN – INcoming SOLAr radiaTION a. Through the seasons, it heats our world, some parts more and some less Indirect Rays Direct Rays

Solar Electromagnetic Spectrum The solar electromagnetic spectrum includes visible light, as well as X-rays, ultraviolet rays and infrared rays.

Factors Affecting Insolation – Duration (TIME –How Long) Direct result of TILT & parallelism in orbit distribute energy from vertical to oblique rays Tilt (inclination) spreads concentration of energy over broader area

Causes of Weather b. This UNEVEN HEATING causes earth’s atmosphere to react and become a gigantic engine that produces an infinite variety of WEATHER .

A. Weather/Atmospheric Variables Temperature Air Pressure Moisture Conditions ( Precipitation & Humidity ) Wind (Speed & Direction)

Weather Instruments Barometer – measures AIR PRESSURE

Weather Instruments Pyschrometer – measures amount of water vapor (relative humidity) Rain Gauge – Measures liquid precipitation

Weather Instruments Wind Vane – measures wind direction Anemometer – measures wind speed

Weather Instruments Thermometer – measures air temperature Note: In the USA we still use degrees Fahrenheit – the rest of the world measures in o Celsius

B. Atmosphere = The envelope of air (mixture of gases) that surrounds Earth. Composition of the lower atmosphere (troposphere): 1. Nitrogen = 78% used by bacteria in soil to make nitrates 2. Oxygen = 21% used by humans and animals for respiration 3. Argon = 0.84% 4. Carbon Dioxide = 0.03% used by green plants to make food

B. Atmosphere 5. Others = 0.01% which include: Helium, Hydrogen, Ozone, Krypton, neon and xenon 6. Also: water vapor, dust particles and pollution

Bill Nye The Science Guy Atmosphere Part 1 Atmosphere Part 2 Complete the worksheet in the note packet while you watch!

B. Atmosphere 1. Composition vs. Altitude Layers of the Atmosphere (Reference Tables Pg 14 )

B. Atmosphere 2. Atmosphere and Solar Energy

B. Atmosphere 2. Atmosphere and Solar Energy 6% reflected from atmospheric scattering (aerosols) 20% reflected by clouds 4% Reradiation: Reflected by Earth’s surface 3% Absorbed by clouds 51% Absorbed by Earth’s surface 16% Absorbed by atmosphere

C. Temperature and Heat 1. Heat Transfer CONDUCTION – Transfer of heat within solids atoms are closely packed.

C. Temperature and Heat 1. Heat Transfer CONVECTION – Transfer of heat in liquid or gas results from differences in density

RADIATION : The emission or giving off of energy HEAT

2. Measuring Temperature Heat in the atmosphere is recorded as a temperature reading and can then be plotted on a map to see a picture of change. Reference Table Page 13 If you need to convert temp. – use the ESRT ISOTHERMS are lines that connect points of equal temperature. Showing temperature distribution in this way making patterns easier to see.

Isotherms on Synoptic Weather Map Why do the isotherms seem to run E – W across the map?

3. Factors that Effect the Amount/Rate of Heating Duration and Angle of Insolation

3. Factors that Effect the Amount/Rate of Heating LAND vs. WATER Land heats up and cools faster than water

3. Factors that Effect the Amount/Rate of Heating Color DARK vs. LIGHT Darker colors tend to absorb more insolation than they reflect. Surfaces with lighter colors tend to reflect more insolation than they absorb.

3. Factors that Effect the Amount/Rate of Heating TEXTURE Smooth vs. Rough A surface which has a rough or uneven surface will absorb more insolation.

A surface which is smooth will reflect more than it will absorb

D. MOISTURE 1. Changes in State Evaporation – The change in state from liquid to a gas, such as liquid water into water vapor, also called vaporization. It requires 2260 Joules of energy (heat) to convert 1 gram of liquid water to gas. Evaporation is a cooling process since it absorbs heat from the environment

D. MOISTURE 1. Changes in State Condensation – The changing of a gas or vapor to a liquid. Water molecules LOSE or release energy equivalent to what was absorbed during evaporation. Condensation in the atmosphere results in the formation of clouds and dew/fog/frost.

D. MOISTURE 1. Changes in State Melting – Changing of a solid to a liquid It requires 334 Joules of energy/heat to convert 1gram of ice to liquid water. Melting is a heating process. Freezing – Changing of a liquid to a solid Water molecules Lose energy equivalent to what was absorbed during melting.

D. MOISTURE 1. Changes in State e. Phase Change Diagram

D. MOISTURE 1. Changes in State Sublimation – The change of state from a solid directly to a gas with no liquid state in between. Examples: Moth Balls and dry ice Deposition – gas changing directly to a solid Ex. Frost

Use your review book – page 118 and the ESRT to complete your worksheet

D. MOISTURE 2. Moisture in the Atmosphere The primary source of moisture for the atmosphere are the OCEANS . Other sources include: Lakes, Rivers, streams Transpiration Moisture in the atmosphere exists in all three states/phases. Gas – known as water vapor Liquid – tiny droplets suspended in the air that form clouds Solid – tiny crystals suspended in the air that form clouds

D. MOISTURE 2. Moisture in the Atmosphere HUMIDITY is the general term used to describe the amount of water vapor in the air Temperature determines the amount of water vapor the air can hold.

D. MOISTURE 2. Moisture in the Atmosphere As air temperature INCREASES , the amount of water vapor the air can hold INCREASES .

D. MOISTURE 2. Moisture in the Atmosphere Saturation – 100% humidity in the atmosphere (precipitation results) At 35 0 C, a cubic meter of air can hold 35 g/m3 of water vapor.

Factors Affecting the Rate of Evaporation Temperature – As temperature increases, evaporation increases Rate of evaporation Temperature

Factors Affecting the Rate of Evaporation Wind – As wind increases, evaporation increases Surface Area – As surface area increases, evaporation increases

Factors Affecting the Rate of Evaporation Humidity – As humidity goes UP , evaporation rates go DOWN Rate of Evaporation Humidity

2. Dew Point Temperature The temperature to which air must be cooled to reach saturation. And Condense…….and make clouds! When the dew point is close to the current air temperature then humidity is high.

2. Dew Point Temperature The drier the air, the faster/more evaporation will occur resulting in greater/more cooling. In turn, the difference in temperature between the dry bulb and wet bulb will be greater/more .

2. Dew Point Temperature The more humid the air, the LESS evaporation will occur resulting in LESS cooling of the wet bulb thermometer. In turn, the difference in temperature between the dry bulb and wet bulb will be LESS At saturation (100% humidity), the temperature difference between the dry bulb and wet bulb would be zero and precipitation will usually occur! .

3. Relative Humidity Maximum amount of water vapor the air can hold at a given temperature. The actual amount of water vapor in the air is the absolute humidity. Relative humidity tells "how full" the air is with water. It is expressed in %. 100% is full and can't hold any more. It is saturated . Warm Air = higher humidity (wet) Cold Air = low humidity (dry)

3. Relative Humidity Changing Air Temperature 1. If temperature increases and moisture in the air remains the same, relative humidity will decrease.

3. Relative Humidity Time of Day: 1. Highest Relative Humidity = coolest time of day ~ 5:00 am 2. Lowest Relative Humidity = warmest time of day ~ 3:00 pm

3. Relative Humidity Changing Absolute Humidity Temperature Relative Humidity 1. If moisture content of the air increases and temperature stays the same , relative humidity will increase .

It’s easy; if….. You have ½ a brain Pay attention Do your practice! Using the ESRT to determine Dew Point & Relative Humidity Handy Dandy Earth Science Reference Tables Page 12

The “Dry Bulb” Don’t let it fool you. It is just a thermometer. It measures the air temperature. Duh! 20 °C

The “Wet Bulb” Has a little wet booty tied to the bottom. Gets cool when water evaporates. 12 °C Wet Booty

A Dry Day… A lot of moisture will evaporate. The wet bulb will be a lot cooler than the dry bulb. 20 °C Difference between wet bulb & dry bulb is 12 °C. 8 °C 20 °C 14 °C 12 °C

A Humid Day… A little bit of moisture will evaporate. The wet bulb will not be much cooler than the dry bulb. 14 °C 20 °C Difference between wet bulb & dry bulb is 6 °C.

of your Handy Dandy Earth Science Reference Tables Warning #1: Be sure to READ the correct chart: DPT or RH Warning #2: Dew Point Temperature IS NOT “Difference between wet bulb and dry bulb”. Warning #3: The wet bulb temp IS NOT the DPT.

Dry-bulb temperature is your air temperature. 20 °C

Subtract (the difference) between the dry bulb and wet bulb

8 °C 20 °C 20-8=12 Put it all together Relative Humidity = 11%

10 °C 14 °C 14-10=4 Relative Humidity = 60%

10 °C 14 °C 14-10=4 Dew Point = 6°C The Dew Point Chart works the same way

Try These. 57% 17 °C 86% 4 °C 57% 4 °C Now do the worksheet for homework on the next page of your notes 8 °C 12 °C 5 °C 6 °C 20 °C 26°C DPT R Humidity Wet Bulb Dry Bulb

Clouds Adiabatic Cooling - As air rises , the atmospheric pressure surrounding the parcel of air decreases. Therefore, the parcel of air expands as it rises.

Clouds As it expands, it becomes cooler . When the temperature of this parcel of air falls to its dew point temperature , the water vapor in the air condenses and a cloud appears in the sky.

Components of Weather E. Air Pressure What is pressure? The weight of a column of air – this creates air pressure HIGH LOW High pressure is cold air sinking (More Dense) Low pressure is warm air rising (Less dense)

E. Air Pressure Air pressure acts equally in all directions ; it also exists within any object containing air like a building, the human body and “empty” bottles. When you mess with the pressure – “bad” things happen!~ CRUSH!

2. Changes in Atmospheric Pressure Factors/Variables that cause atmospheric pressure to change: Temperature Moisture Altitude Effect of temperature on air pressure: As air temperature increases ; (air molecules move further apart/become less dense) – the air pressure decreases

2. Changes in Atmospheric Pressure c. Effect of moisture on air pressure: As humidity increases , air pressure decreases – because when water vapor molecules enter the air, they replace heavier air molecules

2. Changes in Atmospheric Pressure Effect of altitude on air pressure As altitude increases , air pressure decreases (less air is above and air is less dense

3. Mapping An Air Pressure Field Isobars are lines that connect points of equal air pressure. Showing air pressure distribution in this way makes patterns easier to see. On U.S. Weather Bureau maps, the interval between isobars is 4 mb .

3. Mapping An Air Pressure Field On weather maps, barometric pressure is represented by a three-digit number to the upper right of a circle; this circle represents a city on the map. 053

3. Mapping An Air Pressure Field Rules to follow to determine the value of this number: A decimal point is omitted between the last 2 digits on the right. The number 9 or 10 is omitted in front of this number. If the original number is above 500, place a 9 in front. If it is below500, place a 10 in front. (Hint: use whichever will give a result closest to 1000 mb) Example: 053 – 1005.3

Your map should look like this!

Components of Weather High Pressure System: Anticyclone

Anticyclones Winds blow in a clockwise direction and away from the center Caused by: More dense air “falling”

Components of Weather Low Pressure System: Depression or Cyclone

Or……Cyclones Winds move Counterclockwise and IN towards the center Therefore – once they get to the middle, there is nowhere to go but UP

Wind The horizontal movement of air parallel to Earth’s surface. All wind deflects to the RIGHT in the Northern Hemisphere!

How is Wind Formed? Sun heats ground Ground heats air Air rises and cools in the atmosphere As air cools it can no longer rise Cold air sinks WIND moves between high and low pressure LOW HIGH

A. What Makes the Wind Blow? Uneven heating at Earth’s surface Examples: Land vs. water Poles vs. equator Dark forest vs. snow field

B. Wind Direction and Speed Winds are named for the direction that they come FROM

Wind Direction and Speed Winds always blow from regions of high pressure to regions of low pressure.

2. Wind is represented by this symbol at a weather station : The direction of the line always points to the center of the circle (in this case pointing east) and indicates the direction in which the wind is blowing at this location. Each “feather” represents the wind speed – Whole feather = 10 knots Half feather = 5 knots feather

Now You Try It 15kts 45kts 25kts 20kts 30kts 40kts 35kts

B. Wind Speed and Direction The speed of the wind is determined by the difference in air pressure. Pressure gradient – difference in air pressure ÷ distance between cities. As the pressure gradient increases (isobars are very close together), wind speed increases .

Surface Winds on a synoptic weather map

Coriolis Effect The coriolis effect – Earth’s rotation on it’s axis causes winds to be deflected to the right in the northern hemisphere and to the left in the southern hemisphere.

Profile View Buffalo Boston Buffalo Chicago

Global Winds The unequal distribution of Insolation causes unequal heating of the Earth which causes differences in pressure which result in winds. Cooler air, being more dense , sinks toward Earth due to gravity, causing warmer, less dense air to rise

Global Winds Earth’s rotation causes the Coriolis Effect which results in the three (or six) cell circulation of winds as illustrated in your notes. Earth Science Reference Table pg 14

Components of Weather F. Air Masses What is an Air Mass? An air mass is a large body of air in the troposphere moving in a particular direction, with the same temperature , pressure and humidity throughout.

Components of Weather Air Masses Affecting the U.S.

1. Source Region = Place on Earth where an air mass forms 2. Types of Air Masses Tropical – originates in the tropics (low latitudes). Characterized by warm air . Polar – originates in polar regions (high latitudes). It is characterized by cold air . Arctic – originates in ice covered arctic regions (winter only). It is very cold and dry.

Types of Air Masses Continental – think LAND. It is dry . e. Maritime – think SEA. It is wet . 3. Air masses are a combination of temperature and moisture conditions. It’s right here in ESRT Pg 13

4. Fronts – the interface between 2 different air masses Types of Fronts Cold Warm Stationary Occluded ESRT pg 13 – What it looks like on a weather map!

Warm Front Cold Front Occluded Front Stationary Front: Warm and Cold air meet head on and neither gives way. Low pressure usually “track” along a stationary front bringing heavy, steady precipitation Thunderstorms, lightning, tornadoes Brings intense change – brief periods of stormy weather (severe) Covers wide area Wind changes “ bullies” the warm air UP quickly Lots of Clouds as air rises up precipitation Air is dense and hugs the ground Showers for long period Cold air meets warm air and mixes Cold Air –moves fast Warm air

Station Models IT’S in the ESRT!

Weather Map Symbols IT’S in the ESRT!

Hurricanes A hurricane is a heat engine that gets its energy from warm ocean water . These storms develop from tropical depressions which form off the coast of Africa in the warm Atlantic waters. When water vapor evaporates it absorbs energy in the form of heat. As the vapor rises it cools within the tropical depression, it condenses , releasing heat which sustains the system. A tropical depression becomes a hurricane when its sustained recorded winds reach 74 mph. Although hurricane forecasting has improved over the years tremendously, the path of these storms may only be approximated.

Meteorology

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Meteorology