Earth’s Heat Budget and Temperature Distribution

How the Air Gets Heated

Four Ways Heat Moves

• Conduction passes heat directly between two things touching each other, like the ground warming the air just above it, until both reach the same temperature.
• Convection carries warmed air near the ground upward as rising currents. This vertical transfer only happens within the troposphere.
• Advection moves heat sideways, through horizontal air movement. North India’s hot “loo” wind in summer is a direct result of advection.
• The Sun heats the ground first, in short waves. The ground then re-radiates that heat as long waves, which is what actually warms the atmosphere above it.

The Heat Budget: A 65-Unit Balance

• Of all incoming insolation, 35 units are reflected straight back to space before ever warming anything. This reflected share is Earth’s albedo.
• The remaining 65 units are absorbed: 14 within the atmosphere itself, and 51 by Earth’s surface directly.
• Earth radiates its 51 units back out. Of these, 17 go directly to space, while 34 are re-absorbed by the atmosphere first.
• Adding it up: 17 units from Earth plus 48 units radiated by the atmosphere equals 65, matching the 65 units absorbed in the first place. Nothing is lost or gained overall; this same balancing logic, applied across latitude bands rather than the whole globe, is explored further in our dedicated Insolation article.
• The zone between 40°N and 40°S has a net radiation surplus. The poles run a deficit instead, and winds carry the extra tropical heat poleward to balance it out.

Reading Temperature Around the World

What Controls Local Temperature

• A place’s temperature depends on its latitude, altitude, distance from the sea, the air masses and ocean currents passing by, and local land aspect, the same factors explored by latitude in our Globe and Heat Zones article.
• Temperature normally drops about 6.5°C for every 1,000 metres of height gained, the normal lapse rate. This is why hill stations stay cooler than the plains below them.
• Land heats up and cools down fast. The sea does both slowly, so coastal places see far smaller temperature swings than places deep inland.
• Isotherms are lines joining places of equal temperature. They generally run parallel to latitude lines, since latitude is temperature’s biggest driver, tied closely to Earth’s tilt and its seasonal motion covered in our Motions of the Earth article.
• In January, isotherms bend north over the North Atlantic Ocean, since warm currents like the Gulf Stream keep it milder. Over land, they bend south instead, as the land cools faster. The Siberian interior sees a temperature range over 60°C between January and July, the largest range anywhere; near the equator, the range can be as small as 3°C all year.

Temperature Inversion

• Normally, temperature falls with height. In an inversion, this flips: temperature actually rises with height near the ground instead.
• A long, clear, still winter night is the classic setup. The ground radiates its heat away all night, so by early morning it is colder than the air just above it.
• Inversion traps smoke and dust in a stable layer near the ground, which is exactly why dense winter fog is so common in the early morning.
• In hills and valleys, cold night air flows downhill like water and pools on the valley floor. This protects crops on the upper slopes from frost damage.