Edited and updated by Carol Hopper Brill & Chris Petrone.
Photo courtesy of NOAA.
Coastal Storm Data Activity #3: And The Lows Go Round And Round
North Atlantic low pressure systems always rotate counterclockwise. Why? The rotation stems from the Coriolis Force, which is caused by the rotation of the earth on its axis. As the warm, wet air in a low pressure system rises, it draws air toward its center. The Coriolis Force deflects wind to the right, resulting in a counterclockwise pattern of windstreams around the low.
Identifying Lows
Go to an example weather map. Look at the isobars, the solid lines that form curving patterns on the map. They are usually measured in millibars (mb) of pressure. Where the isobars close around a low value, you have a Low. Where they close around a high value, it's a High.
See another example weather map.
Data Activity & Discussion: Identifying Lows
Go to Oceanweather, Inc. On the left, click on North Atlantic, "Southern Region," then click the "Marine Observations" icon at the top of the page.
- Search for Lows -- possible storm centers -- in the Atlantic. If there are no lows in the Southern region, try the view of the Northern region. If you find a low(s), record the latitude and longitude.
- What direction do the wind vectors point around the low?
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