Solar Radiation and Water Temperature

Abstract

Temperature is a measure of the heat content of an object which results from the energy content of that object. The main source of energy in ecological systems is solar radiation. The earth’s energy budget is essentially balanced with the incoming solar radiation being balanced by the reflection of solar radiation and the re-radiation of energy absorbed by the earth as longwave radiation. The temperature of natural water bodies vary in response to diurnal and seasonal changes in solar radiation. The penetration of light into water bodies which regulates the depth to which photosynthesis occurs is strongly influenced by water clarity. Solar radiation heats the surface layers of water in lakes, reservoirs, and ponds more quickly than it warms deeper water. Water bodies often experience thermal stratification in which warmer, lighter water of the surface layer does mix with cooler, heavier deeper water. Warmth also favors greater rates of most chemical and physical process, and respiration of organisms increases with greater temperature within the temperature tolerance range of organisms.