Question: What is wind

Steven Gardner answered on 19 Jun 2013:

Wind is caused by the heat from the Sun, the sun heats up the air, which then rises because it is less dense. Other air then rushes in to take it’s place, and this is wind.

Tracking wind around the earth is enourmously complicated! The UK met office (which produces the weather forecast) use two supercomputers to do the calculations, and even then they’re often wrong!