21/10/2010 The Global Heat Budget

2 absorbed by clouds and dust, water vapour and other gases in the atmosphere absorbed by surface reflected by clouds and dust, water vapour and other gases in the atmosphere reflected by surface 100% 19% 26% 55% 4% 51% Solar Insolation

3 absorbed by surface reflected by atmosphere reflected by surface 100% 19% 26% 55% 4% 51% absorbed by atmosphere solar insolation reaches surface TOTAL ALBEDO = = 30% TOTAL ABSORPTION = = 70% Solar Insolation ALBEDO = REFLECTIVENESS

4 Tasks: 1.Copy figure 2.2 into your jotter. 2.Answer all of question 3 on page 32

5 Energy Receipt and Latitude Need to be able to: 1.Describe variations in the amount of solar energy reaching the earth’s surface by latitude. 2.Explain which areas of the world (by latitude) receive more solar energy and the reasons why.

6 Exam Question With the aid of an annotated diagram of the earth, describe and explain the latitudinal variation of the Earth’s energy balance? Use Figure 2.3 on page 7 to help What is this question asking? 1.DESCRIBE the variation in solar energy at different latitudes – notably the tropics and polar regions 2.EXPLAIN why this variation occurs – i.e. why does what you are saying to the first part of the question actually happen

7 Energy Receipt and Latitude Tasks: 1.Make a neat copy of diagram 2.4 and label it. 2.Study figure 2.3 describe the areas of energy surplus and deficit. 3.Using page 6 give 3 reasons why there is a net gain of energy in the low tropics. 4.Find 3 reasons why the poles are an area of energy deficit.

8 The Earth's atmosphere is put into motion because of the differential heating of the Earth’s surface by solar insolation. The Poles receive less heat than the Tropics because: 1.Insolation has to pass through more of the Earth’s atmosphere 2.The angle of incidence of insolation 3.Higher levels of surface albedo. ENERGY SURPLUS and DEFICIT

Insolation has to pass through more of the Earth’s atmosphere The angle of incidence of insolation - energy is spread out over a larger area because the sun’s rays strike the surface at a lower angle. Higher levels of surface albedo - the ice-cap reflects more solar insolation IT IS VERY IMPORTANT TO PRACTICE / LEARN A VERSION OF THIS DIAGRAM