ABSTRACT
Winds are generated by uneven heating of the Earth and its atmosphere by the sun. The Earth is generally warmest at the equator. As the air there is heated, it expands. (Remember Charles and Gay-Lussac—increasing the temperature of a gas increases its volume.) The same mass of air now occupies a larger volume, another way of saying that the density of that portion of air has decreased. Because the density has decreased, the air will rise. This expansion by heating and reduction of density is the origin of the bit of folk wisdom that ‘hot air rises.’
