These winds became known as the "Krakatoa easterlies". The winds were then called the Krakatau easterlies. Embedded within the deep easterlies, the depression tracked west-northwestward at . Strong low level easterlies and rapid westward movement led to slower development thereafter. Because of the Indian Ocean Walker circulation there are no continuous equatorial easterlies. Downward motion of the easterlies is usually more irregular than that of the westerlies. Strong upper level easterlies halted development due to vertical wind shear. The air flows at the surface are called the polar easterlies. Near the poles easterlies created a subpolar gyre that rotated clockwise. Major SSWs occur when the winter polar stratospheric westerlies reverse to easterlies. Fog is common in winter mornings, namely in June when moist easterlies dominate. Another weather system produced easterlies in western Asia during the same period. Westerly winds are most frequent in the mid-latitudes while easterlies dominate the tropics.