The Variations In Evaporation Due To Seasonal Changes

Evaporation Student’s Name Institution Date Introduction Some areas worldwide experience low evaporation rates annually due to the low water content of the soil. For example in the Sahara desert, the evaporation rates here are significantly low due to the dry conditions despite the high solar radiation experienced in this region. However, it is essential to note that in the Nile River with its constant available water, regions closer to this water source experience higher evaporation than the surrounding arid area (Shaw, Beven, Chappell, & Lamb, 2010). This paper will, therefore, provide an overview concerning evaporation. It will include the factors associated with evaporation especially in the tropic regions. It will also discuss the variations in evaporation due to seasonal changes. Evaporation process Evaporation involves the process where water is transformed into vapor on the land surface or that of a liquid. The surrounding gas is not usually saturated with the evaporating component. Once the liquid molecules collide, this leads to the transference of energy towards each other depending on the manner that they collide together (Robinson, & Ward, 2017). Once the molecule nearing the surface absorbs adequate energy to resist the vapor pressure, it then escapes and enters the environment as a gas. Once the evaporation process takes place, the energy is then removed from the vaporized substance which will have a significantly low temperature. This leads to evaporative cooling. On average, only a small fraction of the molecules inside the liquid have enough heat energy to escape from the liquid. The evaporation is a continuous process until equilibrium is gained. Equilibrium is determined once the evaporation of the liquid is equal to its condensation (Shaw, Beven, Chappell, & Lamb, 2010). Inside a restricted environment, the liquid evaporates into the atmosphere which is highly saturated. Factors that affect evaporation Temperature is one of the factors associated with evaporation. As the temperature of the air rises, its ability to contain the moisture will also increase. Any significant temperature increase leads towards an elevated water temperature at the evaporation source. This means that extra energy is available to the water molecules for easily escaping into the atmosphere (Shaw, Beven, Chappell, & Lamb, 2010). Therefore, the temperature of the evaporating surface is directly proportional to the evaporation process. The warmer the surface becomes, the higher the evaporation process rate occurs. Relative humidity is also associated with the evaporation rate. When the vapor pressure is high, the rate of evaporation lowers, especially in tropical regions. This is typical since evaporation is typically greater at the end of summer compared to the middle of the winter season. The speed of the wind also affects evaporation. When the winds are light, this leads to the formation of a thin layer of air which becomes almost saturated. This leads to low evaporation (De Jong, Collins, & Ranzi, 2005). Therefore, when the velocity of the wind is high especially during spring and summer, the turbulence is developed within the air. The moisture that evaporated from the surface is mixed upwards and the difference in vapor pressure from the surface and the atmosphere remains huge. Therefore, when elevated temperatures, a low relative humidity and high-velocity winds combine, the evaporation rate increases. This combination leads to soil dehydration. Also, the evaporation rate is assessed by the exposure level of the water surface (Shaw, Beven, Chappell, & Lamb, 2010). Regions with large evaporating surfaces have an elevated evaporation rate. The air pressure and composition of water are also factors that affect evaporation in tropical regions. Lower pressure on the open surface of the liquid leads to a higher evaporation rate. Evaporation is typically inversely proportional to the water salinity (Peters, 2016). The evaporation rate is always higher over fresh water and salt water. Under similar conditions, the ocean water usually evaporates almost five percent more slowly than the fresh water. Overview As highlighted above, the rate at which evaporation occurs is influenced by temperature, sunshine, wind and humidity. Temperature and sunshine are highly important factors. Ultimately climatic zones and seasons mean various areas of the globe experience varying evaporation rates annually (Laîné, Nakamura, Nishii, & Miyasaka, 2014). During the summer months which are July and August in the Northern Hemisphere and December, January and February in the Southern Hemisphere, the high energy input emitted by solar radiation means that there will be higher rates of evaporation in the winter months will be experienced. There is a huge possibility that evaporation has a warming effect n the global climate since water vapor acts as a greenhouse gas when emitted into the atmosphere. Also, the energy absorbed by the evaporated water is normally released back into the environment once the vapor condenses and returns to the surface as rainfall (Worden, et. al, 2007). Globally, this cycle of evaporation and condensation moves energy around but they cannot independently or rapidly affect the worldwide equilibrium of energy within the earth’s surface. The evaporation process rises simultaneously as temperature increases. Also, the holding capacity of the moisture in the atmosphere is elevated with temperature. Therefore, for every increase of ten degree Celsius of the global temperature, there is a seven percent decrease in the moisture capacity that holds the atmosphere (Peters, 2016). Also, additional moisture in the atmosphere leads to fluctuations in rainfall patterns. Evaporation heavy relies on the availability of water. For instance, more water can be evaporated and condensed from a huge water source such as an ocean. Moist regions such as tropical rainforests experience elevated evaporation rates compared to arid areas. The amount of evaporated water from the land surface will depend on the water content within the soil (Robinson, & Ward, 2017). A study measuring evaporation from a tropical rain forest in Puerto Rico indicated that such a region receives high evaporation rates. This study focused mainly on the Bisley forest. The study was conducted between1996-1997 (Schellekens, et. al, 2000). 1996 1996 1996 1997 1997 1997 Water balance component Millimeters Millimeters per day Percent of precipitation Milimeters Milimeters Per day Pecent of precipitation Rainfall 3687 10.1 100 3480 9.50 100 Evapotranspiration water budget 2420 6.61 65.6 2179 5.97 62.6 Transpiration water budget 632 1.73 17.1 815 2.23 23.4 Interception water budget 1788 4.88 48.5 1364 3.74 39.2 From the table above, this tropical region received high and consistent rainfall based from the levels of precipitation highlighted. High precipitation levels are directly associated to high evaporation rates which heavy relies on the availability of water. Terrestrial plants typically lose water through transpiration process. Here, water is usually transported by the roots of the plants towards its leaf whereby it is then lost through the surface pores of the leaf. The leaf surface normally intercepts or captures rain and the water can then be evaporated before it reaches the soil (De Jong, Collins, & Ranzi, 2005). Forested areas in tropical regions such as the Amazon forest, is occupied by leaves which intercept rainfall and are essential mechanisms in the inclusion of the process of trying to model the evaporation process. Analysis of evaporative cooling and atmosphere moisture cycling Evaporative cooling refers to the process whereby the local area is cooled by the energy utilized in the evaporation process. This energy would have otherwise heated the surface of that particular area. It is well known that clearing of forests and also the development of the urban area can significantly contribute to local warming (Robinson, & Ward, 2017). This is achieved through the decreased local evaporative cooling. The entire earth surface has been experiencing high temperatures over the past several years mainly as a result of carbon dioxide emission from the bringing coal, gas and also deforestation. However, since water vapor plays numerous roles in the climate system, the global climate outcomes of changes in evaporation are not significant. Atmospheric moisture cycling is a critical component of the climate system of the earth. Direct evaporation of rain is a huge contributor towards the moisture and heat from the clouds. The relative contributions towards atmospheric moisture over land from local humidity and evaporation from water sources are not entirely certain (Laîné, Nakamura, Nishii, & Miyasaka, 2014). Lighter isotopes of water vapor usually evaporate while the heavier isotopes typically condense and the isotopic composition of ocean water becomes identifiable. It is clear that atmospheric water is highly significant to the climate since its capacity to control precipitation is high and also it has a huge influence on the reflection and absorption of solar and terrestrial radiation. Once water changes its aggregate state, energy can either be used up or produced (Worden, et. al, 2007). This is important for the tropical atmosphere whereby condensation of water vapor in large amounts results in the release of latent heat energy. Evapotranspiration The global hydrosphere has numerous water reservoirs which are connected by water fluxes in several stages. In tropical regions, water from these sources moves in a continuous interchange which is systematic of the geographical position and physical state that has been highlighted as the hydrological cycle (Robinson, & Ward, 2017). Evapotranspiration is an important component in the physical process and water budget within the tropics. This process identifies the total flow of water in the atmosphere that is comprised of evaporation and transpiration. Over numerous sub-tropical and tropical regions, the direct contribution of the elevated surface temperature heavily influences the increase in evaporation. This offsets over oceans through contrition made by weakening the surface winds and also an increase in the near-surface that is relative to humidity (Laîné, Nakamura, Nishii, & Miyasaka, 2014). Therefore greater warming of the surface, when compared to the sea surface, acts towards decreasing surface evaporation. This is accomplished by reducing both the exchange coefficient and contrast in humidity within the surface. Distribution of evaporation In tropic regions, the temperature is the main control of evaporation and therefore, the potential evaporation naturally decreases from the equator towards the poles. This can be enhanced when there is an unlimited supply of water. Genera...