Evaporative Water Loss

The surface energy balance of Lake Superior was measured using the eddy covariance method at a remote, offshore site at 0.5-h intervals from June 2008 through November 2010. Pronounced seasonal patterns in the surface energy balance were observed, with a five-month delay between maximum summer net radiation and maximum winter latent and sensible heat fluxes. Late season (winter) evaporation and sensible heat losses from the lake typically occurred in two- to three-day-long events, and were associated with significant release of stored heat from the lake. The majority of the evaporative heat loss (70–88%) and sensible heat loss (97–99%) occurred between October and March, with 464mm (2008–2009) and 645mm (2009–2010) of evaporative water loss occurring over the water year starting October 1. Evaporation was proportional to the horizontal wind speed, inversely proportional to the ambient vapor pressure, and was well described by the ratio of wind speed to vapor pressure. This ratio remained relatively constant between the two water years, so the differences in evaporative water loss between years were largely associated with differences in lake surface conditions (e.g. water temperature, ice cover, and ice duration). Since late-season water temperature decline is driven by evaporative and sensible heat loss, the potential for a negative feedback mechanism between evaporation and ice cover is discussed.

In this study, an attempt has been made to investigate the deformation and moisture transfer behaviour of Shirahama sandstone using small cylindrical samples. A series of comprehensive laboratory experiments were performed in one-dimensional moisture transfer condition under zero confining pressure. Saturated cylindrical samples were dried in a climatic chamber and thereafter rewetted by high air humidity while deformation and evaporative

Pressurized irrigation is quickly replacing surface irrigation systems in Spain due to the impulse of irrigation modernization programs. The change in irrigation system is resulting in reduced labour and increased irrigation efficiency and crop yield. The main constraint for sprinkler irrigation is the wind, which severely reduces irrigation uniformity and increases evaporation water losses. Many areas of Spain are characterized by strong winds, and therefore require specific design and management techniques. Such is the case of certain areas of the Ebro Valley depression, where yearly wind averages can exceed 3 m s −1 . Mathematical simulation models of sprinkler irrigation are required to predict irrigation performance under different hardware, operation and environmental conditions. Such models are based on ballistic theory, and require the numerical solution of the equations of movement applied to a drop moving in the air from the sprinkler nozzle to the soil surface or the crop...

Chinchilla brevicaudata lives at 3500–5000 m, with high ambient temperatures during the day but cold at night. In this Andean habitat there is also low availability of food and water resources. Physiological attributes that may minimize their energetic cost as well as the water requirements are: (1) Low values of basal metabolic rate (67.2%) and thermal conductance (51.0%) compared to predicted values. (2) The aerobic metabolic expansivity was 5.1, while the calculated theoretical critical lethal temperature was extremely low (−67.8°C). (3) The energetic cost for maintenance of water balance was 85.3% of the predicted value for xeric rodents of similar size.

An annual water balance model for Wadi Rajil, in Northern Jordan, is used to simulate the ancient water supply system for the Early Bronze Age site of Jawa. The model includes: water delivery from the catchment; local pond storage; and water demand for people, animals and irrigation. A Monte Carlo approach is used to incorporate the uncertainty associated with a range of factors including rainfall, evaporation, water losses and use. The stochastic simulation provides estimates of potential population levels sustainable by the water supply system. Historical precipitation estimates from a Global Circulation Model, with uncertainty bounds, are used to reconstruct the climate at Jawa in the Early Bronze Age (EBA). Model results indicate that the population levels in the predicted wetter conditions during parts of the EBA could have risen to ∼6000 and may have been higher in wet years. However, palaeoclimatic proxies also suggest prolonged droughts in the EBA; and during these periods t...

Adverse environmental conditions can be evaded, tolerated or modified in order for an organism to survive. During their development, some insect larvae spin cocoons which, in addition to protecting their occupants against predators, modify microclimatic conditions, thus facilitating thermoregulation or reducing evaporative water loss. Silk cocoons are spun by honeybee ( Apis mellifera) larvae and subsequently incorporated into the cell walls of the wax combs in which they develop. The accumulation of this hygroscopic silk in the thousands of cells used for brood rearing may significantly affect nest homeostasis by buffering humidity fluctuations. This study investigates the extent to which the comb may influence homeostasis by quantifying the hygroscopic capacity of the cocoons spun by honeybee larvae. When comb containing cocoons was placed at high humidity, it absorbed 11% of its own mass in water within 4 days. Newly drawn comb composed of hydrophobic wax and devoid of cocoons absorbed only 3% of its own mass. Therefore, the accumulation of cocoons in the comb may increase brood survivorship by maintaining a high and stable humidity in the cells.

1. 1. Virtually all of our knowledgeof avian evaporative water loss is based on open flow determinations, and several generalizations concerned with water loss are based on insufficient information because of limitations in this technique. ... 2. 2. Some characteristics of the ...

 Physiological responses to desiccation and temperature stress as well as behavioural responses to fast and abrupt environmental changes were investigated in high- and low-shore Littorina saxatilis (Olivi) from several populations from the White and North Seas. Variations in evaporation rates, resistance to air exposure and to acute and chronic temperature stress between animals from different shore levels were similar in White and North Sea periwinkles, consistent with the adaptive nature of these variations. High-shore snails were found to be able to conserve body water reserves better, to resist higher temperatures and to survive longer under conditions of combined temperature and desiccation stress than their low-shore counterparts. In a temperature range of 25 to 35 °C, the rate of evaporative water loss was positively correlated with temperature in low-shore snails while being largely temperature-independent in high-shore snails. Median lethal time during air exposure in L. saxatilis was negatively but not linearly related to the temperature of exposure. In a temperature range of 30 to 38 °C, the resistance to heat exposure in air was only slightly dependent on the temperature, with Q 10 = 1.4 for the median lethal time; the heat resistance dropped drastically at temperatures above 38 °C, with Q 10 = 593.8. This suggests different mechanisms of temperature resistance in different parts of the studied temperature range. In contrast, behavioural response to extreme salinity fluctuations was not uniform in the high- and low-shore periwinkles from the White and North Seas, which may reflect specific environmental conditions at different shore levels in the two areas studied. Observed physiological and behavioural variations are discussed from the viewpoint of different adaptive strategies employed by eulittoral and eulittoral-fringe animals within populations of a single species.

From the measurements of the profiles of hydraulic conductance and water potential from soil through to the leaf system in fully established melon plants, the limits to water flow set by coupling of hydraulic conductance (k) with water relation parameters was evaluated in the laboratory using high pressure flow device (HPFM) and evaporative flux method (EF). The rootstock Arava was