Contact: David Hosansky
National Center for Atmospheric Research/University Corporation for Atmospheric Research
Caption: This map of air flow a few miles above ground level in the Northern Hemisphere shows the type of wavenumber-5 pattern associated with US drought. This pattern includes alternating troughs (blue contours) and ridges (red contours), with an "H" symbol (for high pressure) shown at the center of each of the five ridges. High pressure tends to cause sinking air and suppress precipitation, which can allow a heat wave to develop and intensify over land areas.
Credit: Image courtesy Haiyan Teng.
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