Critically Evaluate the factors influencing the Global Heat Budget (40 marks) The global heat budget, also known as the atmospheric heat budget, is the balance between the incoming insolation (solar radiation), and outgoing radiation from Earth. Due to absorption, reflection and scattering throughout the atmosphere, the Earth’s surface only receives 24% of the incoming insolation. Whilst the atmosphere has a net deficit of energy, the surface has a net gain, except for the polar regions. This difference therefore results in movement of energy from the surface to the atmosphere. Several factors affect the amount of insolation and thus the heating of the atmosphere, including latitude, seasons, diurnal range, altitude, ocean currents, cloud cover, human activity, aspect, specific heat capacity and distance from the ocean. Latitude, defined as the angular distance of a place north or south of the equator, is often considered the main factor influencing the heat budget. As the latitude increases, the angle of the sun in the relative sky decreases, causing more insolation to be absorbed or reflected by the atmosphere. The curvature of the Earth results in the insolation spreading out over a larger surface area in more Northerly and Southerly latitudes than at the equator, thus lowering the amount of insolation per km2 at higher latitudes. NASA data indicates that areas around the equator absorbed around 200 W/m2 more on average than were reflected or radiated, whereas areas around the poles reflected or radiated around 200 W/m2 more than were absorbed, leaving mid­latitudes roughly in balance. Therefore it is clear how latitude is considered one of the main factors influencing the global heat budget, in that it affects the total distribution of energy over the Earth’s surface, causing an imbalance between the poles and the equator. Seasons have an effect on the level of