Bath, Pa,
"N O T E"
All weather articles written by the author,
weather records for Bath, Pa. USA, graphs,
graphics, pictures, are copyrighted and are owned by the author.
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please make reference to the: Station Licensee: Virginia T. Giannetta.
Owner - Author: Charles A. Giannetta. Computer Consultant: Charles E. Giannetta
& This Web Site. Thank you.
**Clouds**
"N O T E"
All weather articles written by the author,
weather records for Bath, Pa. USA, graphs,
graphics, pictures, are copyrighted and are owned by the author.
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**Clouds** |
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Any cloud, from delicate wispy ice crystal clouds six miles above the
earth to a pea-soup London Fog, is a portion of air that has condensed
into visibly moisture. Cooling of such a portion of air to its dew point
is the main reason for most cloud formation. The chief cause of cooling lies
in some process which causes air to rise or to be moved upwards.
Large warm air masses may sometimes slide up the slope of a colder heavier
mass of air. As the warmer air overrides the cooler, the warm air expands and
is cooling itself by the expansion of air molecules.
(Rising unsaturated air cools at approximately 5 Degs. F. per 1,000 feet,
or 3 Degs. C. per 1,000 ft. This is know as the Adiabatic Process).
As the warmer air rises and cools, it reaches the dew point, (the
temperature at which condensation occurs), and clouds form.
Air can also rise by being pushed against mountains. This process is
called, (Orographic Lifting). Forced aloft the rising air cools by
expansion and clouds result as we often see along the ridge of the Blue
Mountains. Another way air can rise is in vertical convection currents,
heated from below by a warm surface, which is the first stage in the
development of the thunderstorm. In all cases a cloud in the sky or fog on
the ground is just a version of many familiar everyday forms of
condensation - the expelled breath smoke on a frosty morning or the steam
from a teakettle.
Our atmosphere contains substances which attract water vapor.
Sea salt in the air from oceans, is an example. Chemical wastes from
industrial processes have a very good attraction for water.
These microscopic bits lure water vapor, and are called,
(hygroscopic or condensation nuclei), and play an important roll
in the process of most forms of condensation.
When watervapor condenses into visible moisture, the droplets are
too small to be seen by the naked eye. They gather around the tiny
condensation nuclei in the air - the salt spray, dust, pollen, and
join up in large numbers as a group to form a cloud. Water droplets
are so small, you could put more than 100 million in a teaspoon. At the
center of each droplet of water or ice is even a smaller speck of dust,
salt, smoke.
All clouds consist of large numbers of minute water droplets, ice crystals
or a combination of both. Clouds at very high altitudes
(where below freezing temperatures exist) consist of tiny prisms of ice
formed by the process of sublimation. In this process water vapor turns
directly into ice without going through a liquid stage. Clouds frequently
contain water droplets which may exist as water even at levels where
temperatures are below freezing. These water droplets are said to be
(supercooled).
© 1998 Charles A. Giannetta
