Block (meteorology)
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Blocks in meteorology are large scale patterns in the atmospheric pressure field that are nearly stationary, effectively "blocking" or redirecting migratory cyclones. They are also known as blocking highs or blocking anticyclones.[1] These blocks can remain in place for several days or even weeks, causing the areas affected by them to have the same kind of weather for an extended period of time (e.g.- precipitation for some areas, clear skies for others).[2] In the Northern Hemisphere, extended blocking occurs most frequently in the spring over the eastern Pacific and Atlantic oceans. [1]
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[edit] Omega blocks
Omega blocks are so-named because the height fields associated with them resemble the Greek letter omega. The typical pattern for this is low-high-low, arranged in the west-east direction.[2]
[edit] Rex blocks
Rex blocks consist of a high situated to the north of a low. Very often both the high and the low are closed, meaning that the isobars (or constant geopotential height lines) defining the high/low close to form a circle.[3] Rex blocks are not so-named because they are considered the "king of blocks" (see Rex), but rather they were named after the meteorologist who first identified them.[4]
[edit] See also
[edit] References
- ^ a b Glossary of Meteorology, Second Edition; American Meteorlogical Society, 2000; ISBN 1-878220-34-9.
- ^ a b Brief page about Omega blocks
- ^ Brief page about Rex blocks
- ^ Another Rex Block page
