Name: Roger
Status: student
Grade: other
Location: Outside U.S.
Country: Australia
Date: Summer 2011
Question:
What drives extratropical synoptic high and low pressure
systems to follow particular paths and for forecasters to be able to
forecast that a low will form in a particular location and then move
in a particular way? In Australia a typical situation is for a low
pressure to form off the east coast. Forecasters may predict it may
intensify and move south or dissipate and move east or a number of
other scenarios. Mostly their predictions are correct. What
indicators are they using for them to use as a basis for their forecasts?
Replies:
Roger
High and low pressure areas in the atmosphere are created by Uneven
heating of the earth's surface Forces resulting from the rotation of
the earth on its axis Forces exerted by neighboring weather systems.
Uneven heating results in hot patches on earth's surface.
The air over the hot patches heats up and rises creating an area of low
pressure on the earth's surface.
As this hot air rises, it cools.
The cooler air will then fall back to the surface creating a high
pressure area.
But as time passes as the hot air rises, cools and falls back, the
rotation of the earth causes the cooler air to fall at a different part
of the surface.
And as the cooler air falls it experiences forces from the coriolis
effect
(see: http://en.wikipedia.org/wiki/Coriolis_effect) of the rotation of
the earth on its axis.
Then, weather data from tracking stations all over the world are
assembled into a big picture. This includes local observations by
people, automated stations such as buoys at sea and remote land based
sites, and earth orbiting satellites. The big meteorological picture
is then made available to local weather forecasters who also use local
radar to watch rain and snow as it approaches metropolitan areas. This
gives people long lead times in preparing for severe weather systems such as hurricanes.
More information is available by going to http://www.google.com and
searching for "Weather Prediction".
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