Heating and cooling of the atmosphere

Correct answer: C. It decreases

Warm air expands, so its density decreases and it rises. Exam tip: understand this as the start of convection.

Correct answer: D. Because it has higher density

Direct answer: Option D, because cold air has greater density. When air cools, its molecules move less energetically and, under comparable pressure, the air becomes denser. Denser air is heavier per unit volume, so gravity makes it tend to sink. As it descends, warmer and less-dense air can rise, producing convection and circulation. Option A is wrong because cold air does not come from the Moon. Option B is wrong because air does not pull the Sun; solar attraction is not the explanation for ordinary sinking air. Option C is wrong and is not a physical reason: radiation is not something air can ‘know’. Option D is correct, although pressure and local conditions also affect actual movement. In a convection cycle, heating makes air expand and rise, while cooling makes it contract, become denser and sink. Memory cue: warm air rises; cool, dense air sinks.

Correct answer: A. Because pressure is lower above and air expands

As air rises, it expands and its temperature falls. Exam tip: connect cooling of rising air with expansion.

Correct answer: B. Because it compresses as pressure increases

Downward pressure is higher, so air compresses and warms. Exam tip: link descending air with compressional heating.

Correct answer: C. It can keep night warmer by reducing heat loss

Water vapour absorbs longwave radiation and reduces night cooling. Exam tip: understand humid nights as relatively warmer.

Correct answer: D. Because heating by day and heat loss by night are greater

Dry air has less water vapour, so heat escapes quickly at night. Exam tip: link dryness with large temperature range.

Correct answer: A. Advection

In advection, air horizontally brings heat or cold. Exam tip: link warm and cold waves with advection.

Correct answer: B. Because it brings cool marine air

Relatively cool air from the sea can cool land. Exam tip: consider sea breeze as an example of advection.

Correct answer: C. River erosion

River erosion is a geomorphic process, not a heat transfer method. Exam tip: remember conduction, convection, radiation and advection.

Correct answer: D. Convection

In convection, warm air moves up and cold air moves down. Exam tip: identify convection by actual air movement.

Correct answer: A. Radiation needs no medium and conduction occurs by contact

Radiation occurs without a medium and conduction by contact. Exam tip: understand the difference using sunlight and warm ground examples.

Correct answer: B. Convection is vertical and advection is horizontal

The direct answer is B: convection is vertical, while advection is horizontal. Both are forms of heat transfer by moving air, but their directions differ. Step by step: if air moves upward and downward because of heating and density differences, the movement is convection; if a wind carries warm or cold air from one place to another at the same general level, it is advection. Option A reverses the definitions and incorrectly calls advection underground. Option B is correct: convection is mainly vertical and advection is horizontal. Option C is wrong because neither process occurs only upward. Option D is wrong because neither process occurs only downward. In real weather, movements can combine, but this directional distinction is the standard school definition. Memory cue: convection climbs; advection arrives across.

Correct answer: C. Because evapotranspiration causes cooling

Plants use heat through evapotranspiration and cool surroundings. Exam tip: consider vegetation as a local cooling factor.

Correct answer: A. Because it has less heat and moisture storage

Dry land has less evaporation and can warm rapidly. Exam tip: link lack of moisture with faster heating.

Correct answer: A. Because warm and cold air have different densities

Warm air is lighter and cold air is heavier, so pressure differences can form. Exam tip: link pressure and winds with unequal heating.

Correct answer: A. It affects temperature pressure and wind

Unequal heating and cooling are the basis of many weather processes. Exam tip: connect weather change with energy differences.