Variations in Heat Energy

The Earth as a whole receives 50% of incoming solar radiation, but there are great variations from this average amount of insolation around the world, due to 3 main factors. 1.The Effect of Latitude 2.The Effect of Seasons 3.The Effect of Albedos

The Effect of Latitude on Insolation Within the Tropics, the sun’s radiation strikes the surface at a high angle so; The radiation is used to heat only a small surface area The radiation takes the shortest route through the atmosphere and so loses less heat from absorption and reflection. Near the Poles, the sun’s radiation strikes the Earth’s surface at a low angle so; The insolation is used to heat up a much larger surface area. The insolation passes through more atmosphere and so loses more heat.

Earth Atmosphere Solar Radiation

The Effects of Seasons on Insolation The Earth is tilted on its axis, so radiation strikes the surface at a different angle throughout the year. The Effects of Albedos on Insolation: The Tropics have more vegetation, which has a lower albedo, so more insolation is absorbed The Polar regions have more icy surfaces, which have a higher albedo, so less heat is absorbed.

Redistribution of Heat Energy Areas within 40 degrees of the Equator absorb more solar energy than they emit as terrestrial energy, this is called a POSITIVE HEAT BALANCE Areas beyond 40 degrees absorb less solar energy than they emit as terrestrial energy, this is called a NEGATIVE HEAT BALANCE. Therefore; Since the lower latitudes are not getting hotter and the higher latitudes are not getting colder, there must be a redistribution of energy from the Tropics towards the Poles.

As a sandspit becomes longer, its rate of growth decreases because the water becomes deeper and because the currents speed up as the width of the channel is decreased. When a sandspit reaches across an inlet and rejoins land, it is called a sandbar The enclosed water behind the sandbar is called a lagoon, this slowly becomes filled with sediment, becoming marshy and eventually dry land.

Task 1: If you haven’t already completed it, finish Activity 2 on page 3 of the New Higher Geography textbook. Short-wave Solar Energy Absorbed by Atmosphere 18% 100% 56% 50% Absorbed by Surface 5% 21% 6% Key; Reflection Task 2; 1999 Higher Past Paper Study the diagram opposite. Describe and explain the energy exchanges that result in the Earth’s surface absorbing only 50% of the solar energy which reaches the outer atmosphere.