The California wild fires have begun, and the Santa Ana
winds are mainly to blame. But, how do the Santa Ana winds come to be?
It all starts with high pressure centered to the east of the
Sierra Nevada Mountains. This creates a clockwise flow of air that pushes up
against the Sierra Nevada's. The mountains block the air flow due to their
height and deflect the air to the north and south. The air deflected to the
south is pushed into the dry Mojave Desert which helps to heat and dry out the
air. Dry air corresponds to low humidity values which are a good indicator of a
risk of wild fires. Once the air moves out of the desert, it is moving to lower
elevations (sinking), which in turn means the air is compressing due to higher
pressure, or gaining more internal energy (heat).
The sinking and heating of the air isn't the only thing
causing a problem. When the air moves through narrow canyons, air is forced to
move at higher speeds. The high wind speeds play a huge roll in how easily the
fire will be contained. High winds will further spread flames which can make it
impossible for fire fighters to contain a wild fire.
A Southern California wild fire is currently burning thanks
to these Santa Ana winds. Officials say the fire was 53% contained on Friday,
but has burned through 1,627 acres of land. Winds gusting to 70 mph were
fueling the fire on Wednesday, though have diminished considerably since then.
Despite the calming winds, the state is in a drought which is not expected to
improve as May starts the beginning of the dry season in California.
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Tuesday, September 2 2014 4:33 PM EDT2014-09-02 20:33:01 GMT
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