The heat budget of the earth

In scattering rays spread in different directions instead of remaining straight. In exams remember it by the word spreading.

In reflection rays return after striking a surface. In exams remember reflection by the word return.

The direct answer is B: energy being taken in by an object. Absorption means that a material receives energy instead of merely reflecting or transmitting it. In the Earth’s heat budget, land, water and the atmosphere absorb some incoming solar radiation, and the surface also absorbs some radiation from the atmosphere. The absorbed energy can warm the absorbing body or later be transferred in another form. Option A is wrong because energy going back to space is mainly called reflection or outgoing radiation, depending on the process; it is not absorption. Option B is correct because it gives the simple meaning: an object takes energy in. Option C is wrong because energy may become sound in some situations, but that is not the definition of absorption. Option D is wrong because energy does not simply end; conservation of energy means it changes form or moves elsewhere. A black surface generally absorbs more radiation than a bright reflective surface, which is why it heats more easily in sunlight. Memory cue: absorb means take in; reflect means send back.

Heat budget explains the average energy balance of the whole Earth. In exams keep local weather and global budget separate.

In global average incoming and outgoing energy remain nearly balanced. In exams separate local differences from global balance.

Energy reaching the surface plays a main role in warming Earth. In exams link it with surface heating.

Earth’s heat budget is the balance between incoming solar energy and energy returned to space as terrestrial radiation by the Earth–atmosphere system. Option A refers only to incoming energy, so it is not the complete meaning of heat budget. Exam tip: For a heat budget, remember both energy income and energy loss.

The atmosphere directly receives a part of solar energy. In exams remember atmospheric absorption.

When the surface takes in energy it warms and later warms the air. In exams understand surface as the base of heating.

White snow has high albedo so it reflects more energy. In exams link white surfaces with greater reflection.

Dark soil has low albedo so it absorbs more energy. In exams link dark colour with higher absorption.

Clouds can reduce solar energy by day and trap longwave energy at night. In exams remember the dual role of clouds.

Water vapour is an important greenhouse gas and helps trap terrestrial heat. In exams treat water vapour as a heat trapping gas.

Earth sends energy out through longwave radiation. In exams understand outgoing energy as energy loss.

Solar radiation is the main source of energy gain for Earth. In exams link energy gain with incoming solar energy.

If energy balance changes Earths average temperature can rise or fall. In exams link budget change with temperature change.

Taking hundred units makes reflection absorption and emission easy to explain. In exams treat it as an explanatory model.

Some longwave energy can go directly to space. In exams remember the direct part of outgoing energy too.

The atmosphere can re radiate absorbed longwave energy. In exams link re radiation with greenhouse effect.

The surface absorbs and emits energy and the atmosphere takes part of it. In exams study surface and atmosphere as a connected system.

The direct answer is A: a surface with high albedo reflects more solar energy. Albedo means the proportion of incoming sunlight that a surface sends back. A bright, snowy or icy surface has high albedo, so much sunlight is reflected and less is absorbed. Step by step: sunlight reaches the surface; the surface reflects a large fraction; only the remaining fraction is absorbed; therefore heating is lower. Option A is correct because it states this exact effect. Option B is wrong because high albedo means less absorption, not more. Option C is wrong because albedo does not convert sunlight into sound. Option D is wrong because the surface does not completely stop sunlight; it reflects only a fraction. Memory cue: high albedo means high reflection and generally less heating.

A low albedo surface reflects less and absorbs more. In exams link low albedo with more heating.

Earths surface continuously emits longwave energy. In exams understand terrestrial radiation as a continuous process.

The Sun is a hot source and gives shortwave energy while Earth emits longwave energy. In exams remember this main difference.

Heat budget shows how Earth receives and loses energy. In exams treat it as a base for understanding climate.