Heating and cooling of the atmosphere

Conduction occurs by contact, convection by vertical air motion, advection by horizontal air motion, and radiation by waves. Keep these four processes clearly distinct.

On a clear and calm night the ground loses heat rapidly and cools the air touching it. For exams remember inversion as linked with terrestrial radiation and calm air.

Earth absorbs solar energy and releases heat as longwave radiation warming the lower air. In exams link atmospheric heating with terrestrial radiation.

Air is a poor conductor so heat remains limited to the thin layer in direct contact with the surface. For exams treat conduction as a surface-contact process.

Air over a heated surface expands becomes lighter and rises. In exams connect convection with unstable warm air.

Sea air brings heat and moisture horizontally so temperature becomes moderated. In exams treat this as an example of advection.

Without clouds longwave radiation escapes easily to space. In exams connect clear nights with strong radiational cooling.

Clouds trap longwave heat and counter-radiate it so the surface cools less. In exams remember clouds as a night heat blanket.

Calm air prevents mixing and the surface cools quickly by radiation. For exams remember calm clear nights for inversion.

Deserts have little moisture and cloud so daytime heating and night radiational cooling are strong. In exams link deserts with high diurnal range.

Water vapour and clouds reduce excessive daytime heating and retain heat at night. In exams treat humidity as a factor reducing temperature range.

In convection warm light air rises and transfers heat vertically. In exams rising air is the key sign of convection.

Advection moves heat horizontally while convection involves rising air. In exams separate them by direction of motion.

Land warms more with less heat and does not mix heat deeply. In exams link land-sea contrast with specific heat.

Water changes temperature slowly even after absorbing much heat and currents spread heat. In exams view the sea as a temperature moderator.

During the day slopes heat more and warm air flows upward. In exams remember daytime wind from valley to mountain.

At night slopes cool quickly and adjacent air becomes dense and flows downward. In exams use this as the cause of mountain breeze.

Built surfaces retain heat for longer and release it slowly at night. In exams link urban heat island with surface materials.

Clouds reduce solar energy reaching the surface so daytime heating decreases. In exams daytime clouds usually lower maximum temperature.

By afternoon surface heating lifts moist air which cools and condenses. In exams connect convective clouds with surface heating.

Over long periods balance between incoming and outgoing energy keeps average temperature stable. In exams treat heat balance as an energy budget.

Greenhouse gases trap and re-radiate longwave heat emitted by the surface. In exams remember water vapour and carbon dioxide as key gases.

Horizontal arrival of cold air cools the local air. In exams identify arrival of cold air as cold advection.

When hot air moves horizontally into an area it raises local temperature. In exams treat arrival of hot air as warm advection.

On a clear calm dry night radiational cooling is strong and mixing is weak. For exams remember clear calm conditions for rapid cooling.