If the idealized Earth begins to rotate, the Coriolis force will shift the surface winds to southwest in the Northern Hemisphere, northwest in the Southern Hemisphere. The eastern side of each subtropical high is associated with subsiding stable air, which produces low relative humidities and sunny skies, while the atmosphere at far western side of each subtropical high is less stable and can be associated with cloudy, humid weather. Therefore, the world's major deserts are located at the eastern side of the subtropical high such as the Sahara of North Africa and southwest US which is under the influence of Hawaiian high , particularly in winter, while cloudy, humid weather prevails the southeast US which is under the influence of Bermuda-Azores high , particularly in summer. A subtropical high features a weak horizontal pressure gradient over a broad area at around the system's center. Hence, surface winds are very light or even calm over subtropical oceans.
Subtropical anticyclones exert higher surface pressures in summer than in winter.
They shift toward the poles in spring and toward the equator in autumn. The north to south variation of the subtropical anticyclone has a substantial influnce on seasonal climate. An unexpected nortward shift of Bermuda-Azores anticyclone produces unsusal mild winter weather in the New England, known as January thaw . The westward displacement of Bermuda-Azores high in Ocotober or November is associated with unsual warm weather over the eastern US, known as Indian summer . The nortward shift of North Pacific subtropical anticyclone extends the influence of Bermuda-Azores high westward toward southwestern US where it brings a rainy end to dry spring in late June.