The heat budget of the earth

Earth receives solar energy and sends energy out as terrestrial radiation. In exams this is the simple summary of heat budget.

Heat budget compares energy coming to Earth and energy leaving it. In exams understand it as a global energy account.

Solar energy absorbed by the surface warms the ground. In exams remember the surface as the base of heating.

Terrestrial means related to Earth and it is heat emitted by Earth. In exams understand terrestrial radiation as Earths longwave energy.

Energy from the Sun comes as shortwave and Earth emits heat as longwave. In exams remember this basic difference.

Reflected energy returns after striking a surface or clouds. In exams understand reflection as return of energy.

In absorption energy is taken in by the surface or atmosphere. In exams remember absorption as taking energy.

The direct answer is A: a high-albedo surface reflects more solar energy. Albedo is the fraction of incoming sunlight that a surface sends back. Step by step: sunlight reaches the surface; a high-albedo surface reflects a large part of that energy; less energy remains available for absorption and heating; therefore the surface generally warms less than a dark, low-albedo surface. Option A is correct because reflection is the meaning of high albedo. Option B is opposite: greater absorption is associated with low albedo. Option C is wrong because albedo does not convert sunlight into sound; it describes reflection. Option D is wrong because a surface cannot stop the Sun; it only reflects some incoming radiation. Snow, ice and pale clouds usually have high albedo, while dark soil, forests and oceans generally absorb more. Memory cue: high albedo = high reflection, low heating.

Low albedo means less reflection and more absorption. In exams link dark surfaces with more heating.

Clouds send some solar rays back to space. In exams treat clouds as an important part of heat budget.

Out of hundred units about sixty five units are absorbed by Earth and atmosphere. In exams remember total absorption as sixty five units.

About thirty five units return after reflection by clouds atmosphere and surfaces. In exams link thirty five units with reflection.

Earths surface absorbs about fifty one units of solar energy. In exams remember the surface share as fifty one units.

The atmosphere directly absorbs about fourteen units of solar energy. In exams remember atmospheric absorption as fourteen units.

When Earth’s surface absorbs more solar energy, its heat content and temperature generally increase. Therefore, option A is correct. A fall in temperature would be associated with lower energy absorption or greater energy loss, so option B is incorrect. Exam tip: In the heat budget, greater absorbed energy generally means surface warming.

Outgoing energy leaves Earth and moves toward space. In exams understand it as heat going toward space.

Greenhouse gases absorb and re radiate terrestrial radiation. In exams treat them as heat trapping gases.

Water vapour is a natural greenhouse gas that helps trap heat. In exams link water vapour with heat balance.

Carbon dioxide is a greenhouse gas and can trap terrestrial heat. In exams remember it as an important greenhouse gas.

The atmosphere takes part in energy exchange in several ways. In exams see the atmosphere as an active energy layer.

The direct answer is A, solar rays spread in different directions. Scattering occurs when sunlight meets molecules, dust, smoke, water droplets, or other small particles in the atmosphere. The light is redirected away from its original straight path and travels in several directions. Option A is correct because it states exactly this spreading or redirection. Option B, the Sun disappears, is wrong: the Sun remains present, although atmospheric particles can make its appearance less clear. Option C, Earth’s weight decreases, is unrelated; scattering changes the direction of light, not Earth’s mass. Option D, oceans dry up, is also unrelated and does not follow from scattering. The reasoning is therefore: atmospheric particle → collision with light → change of direction → light spreads. Scattering also helps explain why the daytime sky looks blue, because shorter wavelengths are scattered more strongly, but the essential definition is spreading in different directions. Memory cue: scattering means light is scattered, not destroyed.

Atmospheric particles and gases affect the path of solar energy. In exams treat them as radiation modifiers.

The direct answer is A: snow areas are strongly associated with reflection. Snow is bright and has a high albedo, meaning it sends a large part of incoming solar radiation back into the atmosphere or space. Reasoning: sunlight reaches the snow; the white surface reflects much of it; only a smaller part is absorbed; less absorbed energy means less surface heating. Option A is correct because reflection is the relevant heat-budget process. Option B is wrong because gravity formation is not the process being tested. Option C is wrong because snow does not turn solar energy into sound as a heat-budget process. Option D is wrong because ocean salinity concerns dissolved salts in seawater, not the reflection of sunlight by snow. Snow can melt when energy absorption increases, and exposed dark ground can then absorb more energy. Memory cue: white snow, high albedo, strong reflection, weak absorption.

Dark soil reflects less and takes in more energy. In exams remember dark colour by higher absorption.

The surface emits absorbed energy as terrestrial radiation. In exams remember emission after absorption.