Download Weather Patterns and Severe Weather By Braedyn Taft Earth

Weather Patterns and Severe Weather
By Braedyn Taft
Earth Science
Thomasina Mandan
April 24th 2012
For this assignment I chose Chapter fourteen, it discusses the weather patterns and
severe weather. Since we did not make it to this chapter I thought I’d do my power point on it
so I could learn more about weather patterns and share it with the rest of the class.
The first thing that was talked about in this chapter was violent weather such as
Tornadoes, Hurricanes, and Thun9+derstorms. These three patterns have caused so much
destruction in the world. Most people are familiar with Hurricane Katrina. Thunderstorms are
more common than tornadoes and hurricanes.
An air mass is an immense body of air; it is 1600 kilometers or (1000 miles) across and
several kilometers thick. It is characterized by similarity of temperature and moisture at any
given altitude. Air masses can bring some of the coldest weathers. The air mass is modified, but
it also modifies the weather in the areas over which it moves. It might take several days for an
air mass to move across an area. Constant weather is then known as air mass weather. Air mass
is important because it is closely related to the study of atmospheric disturbances. Disturbances
along boundary zones separate different air masses.
Air masses are classified according to their source region. Polar and arctic air masses
originate in very high altitudes toward earth’s poles. When they form in low latitudes they are
called tropical air masses. So, Polar, tropical, and arctic indicate temperature of an air mass. The
polar and arctic represent cold weather and tropical represents warm weather.
Also, air masses are classified according to the nature of the surface in the source
region. Another term called continental air mass is formed over land whereas, maritime air
masses are formed over water. Continental and maritime have moisture characteristics of the
air mass, but the continental air mass is likely to be dry and maritime’s air is humid. These two
air masses influence the weather of North America the most.
Air mass is a large body of air, usually 1600 kilometers or 1000 miles. It is characterized
by a sameness of temperature and moisture at any given altitude. When this air moves out of
its region it carries temperatures and moisture conditions. It later affects the weather of an
area. The four basic types of air masses are continental polar, continental tropical, maritime
polar, and maritime tropical.
Fronts are boundaries that separate different air masses, one warmer than the other,
and also has higher moisture. Fronts form between two contrasting air masses. These fronts are
usually narrow. The front slopes at a low angle so that warmer air overlies cooler air. Air masses
on both sides of the front move in the same direction and at the same speed. Fronts are said to
act like a barrier, because it move along between the two air masses. When air masses change
to another, mixing occurs. No matter which air mass is advancing it is always warmer and less
dense. The cooler, denser, air acts as the wedge which lifts. Overrunning is warm air gliding up
along a cold air mass.
When the surface position of a front moves so that warm air covers by cool air it is
called warm front. A warm front produced as warm air glides up over a cold air mass.
Precipitation is moderate and occurs within a few hundred kilometers of the surface front. As
warm air ascends the retreating wedge of cold air, it expands and cools to produce clouds and
precipitation.
Cold fronts are the boundary when dense cold air is actively advancing into a region
occupied by warmer air. Friction slows the surface position of a cold front so its position is
aloft. The cold front steepens as it moves because of the relative positions of the adjacent air
masses. The cold fronts are as twice as steep as the warm fronts. A cold front usually comes
from the west or northwest. A dark band of clouds are usually present in the distance. A cold
front produces the same amount of lifting as a warm front.