The air at the equator rises because it's heated by the sun, creating a low-pressure zone. This rising air is replaced by cooler air from higher latitudes. Here's a breakdown:

* Rising Air: The sun's rays hit the equator directly, heating the surface and the air above it. This hot, less dense air rises, creating a low-pressure zone.

* Inflow of Cooler Air: The rising air creates a vacuum, pulling in cooler, denser air from the north and south. This air is called the trade winds.

* Global Circulation: This process is part of a larger global atmospheric circulation pattern. The rising air at the equator eventually cools, creating high-pressure zones at the poles. This air then flows back towards the equator, completing the cycle.

So, in short, cooler air from higher latitudes replaces the heated air at the equator. This constant exchange of air is essential for maintaining Earth's climate and weather patterns.