Next Last Index Home Text Slide 45 of 46 Summary 1.
Air pressure is the driving force for atmospheric motions.
Horizontal changes in air pressure distribution initiate the wind and influences the vertical motions that promote or inhibit cloud formation. The circulation of the upper troposphere is largely the result of latitudinal differences in temperature, with a strong tendency for westerly winds outside of equatorial latitudes. Other atmospheric movements occur in the upper troposphere. The largest and most prominent are the Rossby waves, the large, looping motions of air associated with the jet streams. Adding further complexity to the upper-level winds are short waves and other eddying motions.