Today: Thu 14 Dec 2017

200mb Streamlines and Isotachs

Isotach maps are used for analyzing lines of equal wind speed on a constant pressure surface. They show where the jet stream is located.

  • Purple shading indicates the speed of the winds at the 200 millibar level, in meters per second. This altitude is near the level of the core of the jet stream. So the tracks of the jet streams can be seen very clearly.
  • The streamlines indicate the direction of flow of the wind, which is generally from west to east throughout most of the subtropics, mid- and high-latitudes.
  • The color of the streamlines indicates a relative measure of divergence of the flow in the upper troposphere. Orange and red indicates strong divergence at upper levels, usually associated with strong vertical velocities in the middle troposphere, and severe weather/heavy rainfall.

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