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Monster Media 1996 #14
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Monster Media No. 14 (April 1996) (Monster Media, Inc.).ISO
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math
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wethr53a.zip
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WETH-1.___
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MORE.TXT
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1995-03-25
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Clouds are often associated with low pressure areas.
When the air pressure drops, the air can hold less water
and clouds form. For the opposite reason you rarely see
clouds under high pressure conditions. Clouds are formed
from water that evaporates from the earth. The water vapor
collects as very small droplets on dirt and dust particles
when either the air pressure or temperature drops enough.
Adiabatic Rate is the rate at which the air temperature
falls with altitude. These rates are calculated in degrees
per 1000 feet. There are different rates depending whether
you're calculating below the clouds, or in the clouds.
These rates can be affected by local conditions, but are
used as a good, standard measurement.
Assuming you don't have fog conditions, the Dry adiabatic
rate starts at ground level. This rate is 5.5 degrees F.
per 1000 feet. The Wet adiabatic rate varies, but it is
2 to 5 degrees F. per 1000 feet. The following
diagram helps explain this process:
Wind Direction --> Clouds formed by Orographic Lifting.
_ _ _
Above condensation level, ▒░ / \ As the air descends,
cooling takes place at 3.3 ░▒░▒ / \ it is no longer sat-
degrees F. per 1000 feet. \ \ / \ urated and therefore
/ \ warms at 5.5 degrees
Wind ░▒░▒░▒░ ____/ \ F. per 1000 feet.
Direction --> ░▒░▒░▒░▒░ / \
\ \ \ \ _/ <-- Condensation \__
Rising air cools \ \ \ / Begins \
before condensation / \
at 5.5 degrees F. / (Mt. Shasta) \
per 1000 feet. /________________________________\
Water vapor affects weather and climate in three ways:
1) Water vapor is the only gas in the atmosphere that
condenses under normal atmospheric conditions.
2) Water vapor is the most important gas in our atmosphere
for absorbing both shortwave solar radiation and long
wave terrestrial radiation (radiation given off by
Earth). Thus, water vapor is critical in regulating air
temperature near the Earth's surface.
3) It is a source of 'latent' or stored energy. This is
the energy that drives the movement of air masses over
the Earth. Latent heat is the heat energy gained and
stored by water molecules as they change state from ice,
to water, then to vapor. Latent heat energy is moved
and expended over large areas of the Earth.
Evapotranspiration is the process by which plants return
water vapor to the atmosphere. This quantity is quite
substantial in farming communities. The
irrigation/evapotranspiration cycle is what's known as a
'consumptive' use because it does not return water to the
local vicinity.
Our great, natural deserts are primarily around the 30
degrees north and 30 degrees south regions of the equator.
Why? Those are the areas in between some of the major
global wind patterns. These are caused by the 'Coriolis
Effect' which is prompted by the Earth's rotation. In the
northern hemisphere, this area is between the Northeast
Trade winds, and the Westerlies. Old time sailing ships
were known to get stuck in these areas for months on
end...many unknowing people died.
------------------------------------------------
- Seasons -
The Meteorological Season is from September 1 to August 30.
Summer Solstice : June 21 (summer starts)
Autumnal Equinox : September 22 (autumn starts)
Winter Solstice : December 21 (winter starts)
Vernal Equinox : March 20 (spring starts!)
Maximum Temperature : Late July
Minimum Temperature : Late January
High radiant energy absorbed : About June 20
Low radiant energy absorbed : About December 20