English physicist and meteorologist who first formulated an accurate theory describing the trade winds and the associated meridional (north-south) circulation pattern now known as the Hadley cell.

Though educated in law, Hadley preferred physics to legal work. For about seven years he was in charge of the meteorological observations prepared for the Royal Society of London. Having made the first adequate study of the trade-wind currents, he explained their relation to the Earth's daily rotation and discussed the relevant atmospheric motions and their causes. He presented his ideas in a paper, “Concerning the Cause of the General Trade Winds,” before the Society in 1735. His formulation, however, remained unacknowledged until recognized by the famed British scientist John Dalton in 1793.