Critically evaluate the factors influencing the global heat budget
CRITICALLY EVALUATE THE FACTORS INFLUENCING THE GLOBAL HEAT BUDGET - 40 MARKS The global heat budget is the balance between incoming insolation, and outgoing radiation from Earth. There are many factors that influence this heat budget, some of which are more important than others. In this essay I am going to describe and explain each factor involved. Insolation is the incoming energy from the sun in shortwave ultraviolet (UV) radiation. The distribution of insolation over the Earth’s surface is complicated; however there are patterns to be seen. Insolation has numerous aspects to it that each affects it in turn, which are divided into three categories of long term, short term and local. Quite possibly the most important aspect is latitude, a long term factor. The effect of latitude on the heat budget can be seen all over the globe, but the most striking examples are that the annual amount of insolation in the Arctic region, located 66° north of the equator, is 75 W/m2 however it is 275 W/m2 in Egypt, located 26° north of the equator. Latitude holds such a large effect on insolation because a variation in latitude means variations in the altitude of the sun. Altitude of the sun affects insolation because as the angle of the sun in the sky decreases and becomes more oblique, the land area to be heated up by the rays and the depth of atmosphere they must travel through increase. Therefore the amount of insolation lost through absorption, scattering and reflection increases. Areas in lower latitudes have higher temperatures than those in higher latitudes, because the sun is at a higher angle of incidence. One might expect the highest amount of insolation to be found on land directly below the equator, due to the sun’s highest angle of incidence being located here, meaning the equator receives more energy as solar radiation strikes the Earth head-on. However, as a result of this large amount of sunlight, lots of plant life has grown on land beneath the equator,