Kind: captions
Language: en
a single Cloud can drop rain snow sleet
or hail that's why you may have had the
experience of watching it rain on one
side of town while The Sun Shines on the
other but weather isn't produced One
Cloud at a time even an isolated
thunderstorm is part of a huge weather
pattern that changes with variations in
Wind moisture temperature and air
pressure these weather patterns are
composed of enormous volumes of air that
carry heat and moisture from one region
of the world to another the driving
force for all this movement is energy
from the Sun without it the wind
wouldn't blow and water wouldn't
flow one of the most important details
about the sun's heating of earth's
surface is that it's uneven
just as the sun's intensity varies from
one time of day to another it also
varies from one region to another with
the equator absorbing far more energy
than areas near the poles furthermore
the heat the Earth absorbs doesn't stay
in one place for long it's transmitted
from Earth's surface to the surrounding
air as the air warms relative to its
surroundings it becomes less dense and
begins to rise creating an area of low
air pressure it's sort of an empty space
space or at least an emptier space in
the
atmosphere in response colder denser
High Press air rushes in to fill the low
pressure void creating the movement of
air we know as wind even though it seems
like air would always mix easily volumes
of air with different temperature and
humidity characteristics often don't
scientists refer to a huge volume of air
with particular characteristics as an
air mass air mass es tend to stay intact
and move independently in response to
winds and differences in air pressure by
themselves they can dramatically affect
the weather in areas they move into but
some of the most powerful storms arise
when two air masses meet the area where
two air masses meet is called a frontal
boundary or simply a front the
interactions along these lines which can
stretch for a thousand miles or more can
have a powerful influence on clouds and
weather for example when a cold dense
air mass slams into a warm humid air
mass it forces its way under the warmer
air pushing it up and causing the warm
air to lift and cool this causes the
moisture in the upper air to condense
into clouds and precipitate out as rain
or snow or even hail in some
thunderstorms the greater the
differences in temperature humidity and
air pressure between air mass es the
more likely they are to produce severe
even deadly storms so even if we often
care most about the weather where we are
paying attention to the clouds and
atmospheric conditions on a much larger
scale can give us a heads up about the
weather we might expect in the hours or
days to come