Daily average temperatures in the lower atmosphere are color coded, while predicted wind speeds and directions are indicated by the arrows.
Light winds prevail during equinoctial periods.
At the low levels depicted in the figure, the flow is dominated by eddy activity in both hemispheres. In the northern hemisphere, this activity is centered around the edge of the retreating seasonal frost cap. Because of the strong temperature contrasts at this time, high speed winds are common and local, regional, or global dust storms may occur.