There are several factors that determine the evaporation rate of liquid water. This is important to meteorology since the amount of moisture that evaporates into the air leads to changes in the weather. Below are each of these factors and an explanation: 1. Temperature of water: The water molecules move faster as water warms. The faster the molecules move the more easily they can escape the water surface. A warm lake or ocean will evaporate a large amount of moisture. This moisture can be used to generate precipitation. 2. Temperature of air: As the air above the water warms it has the capacity to have a greater amount of moisture evaporated into the air. If the air is cold it is difficult to evaporate a large amount of moisture into the air even when the water is warm. A combination of warm water and warm air will evaporate the most water. 3. Wind speed: A higher wind helps remove moisture that has evaporated from the water. This helps the relative humidity stay unsaturated near the water surface. When the air is saturated the amount of moisture that evaporates into the air is minimized. Higher winds will continue to supply drier air from aloft to the water surface and this allows for a greater amount of evaporation. A higher wind also churns the water (waves, splashing) and this helps lead to a greater surface area in which evaporation can occur from the water surface. 4. Dry air: Dry air will help generate more evaporation especially if the air is warm and dry. There is a higher capacity to evaporate moisture into the air as the air dries. Once the air is saturated then the evaporation rate is minimized. Air with a low relative humidity is optimum for moisture to evaporate into it. 5. Sunlight: Direct sunlight will lead to more evaporation. The direct photons of light increase the motion of the water molecules it strikes giving them a better chance to evaporate. |