Download - Chautauqua Lake Central School

Climate and Atmosphere Review Sheet
Courtesy of: Pamela J. Shlachtman, Miami Palmetto High School
Objectives:
The student will be able to:
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describe the layers of the atmosphere
understand the pollution of the ozone layer and upper atmosphere
understand lows and highs and frontal systems
understand wind patterns
Structure of the Atmosphere
Most of the air in the atmosphere is within 30 km of the surface. Above 150km, the gas molecules
are very far apart. The atmosphere has been classified into several layers based on composition and
temperature.
Troposphere - Lowest layer, many movements of air, weather from 5-9 miles up. Air temperature
decreases with altitude, usually for every 1000 m, 6.5 degrees C. The troposphere officially ends
when the temperature no longer drops with altitude.
Tropopause - The highest region of the troposphere, very low temperature, ice clouds only,
averages 60 below.
Stratosphere - About 48 km above the earth. Gases are about the same as the ones in the
troposphere only a lot less. Clouds are rare as there is little water and less particles. Only
noctilucent (glow in the dark) clouds are seen in the stratosphere. Temperatures vary from -55
degrees C in the lower layer to -2 degrees C in the upper layer. In the upper layer, there is a layer
of ozone. The ozone layer keeps the ultra violet light from frying the earth. About 90% is absorbed
by the ozone.
Stratopause - Characterized by high temperature due to the ozone reactions that produce heat.
Mesosphere - The temperature drastically drops in the mesosphere to -110 degrees C. It contains
very strong winds , blowing from east to west in the summer and west to east in the winter.
Mesopause - The lowest temperatures in the atmosphere are in the mesopause, -110 C or lower.
Thermosphere - Uppermost layer of the atmosphere. Generally fades out into space. Chemical
composition is not the same as the other layers and tends to have single elements and ions. eg...not
O2 but O, many helium and hydrogen atoms. Temperature rises to about 600 degrees C. Contains
the ionosphere - high energy solar rays crash into atoms and molecules causing ions to be formed.
This area is between 80km and 200km above the earth and is designated the ionosphere. During
periods of increased sunspot activity, the ionosphere glows into what is called an aurora. The aurora
borealis is the northern lights and the aurora australis is the southern lights.
Exosphere - The last part of the thermosphere about 480 km from earth; Very small numbers of
molecules and atoms. most are helium and hydrogen which easily escape the earth's gravity pull into
outer space.
Air Pressure Belts
Around the world are air pressure belts. At the equator, there are the doldrums where the air
moves only slightly. At about 30 degrees north and south, the horse latitudes, representing a highpressure area are found. They got their name because in the slow wind of the 1500s and 1600s, the
ships would be becalmed for days or even weeks and people were forced to throw the horses
overboard. At 60 degrees are the subpolar lows. The winds in between are called the trades (0-30
degrees), the prevailing westerlies (30-60 degrees) and the polar easterlies (60 - 90 degrees).
They deflect to the right because of the Coriolis effect. The pressure area convection current
systems that produce these winds are called the Hadley Cell (0-30 degrees), Ferrell Cell (30-60
degrees) and the Polar Cell (60-90 degrees).
Cyclones and Anticyclones
Not to be confused with the cyclone of the Indian Ocean that is their name for a hurricane.
Cyclones are movements of wind into a low-pressure area. Wind always blows from a high to a low.
Because of the Coriolis effect, the wind blows into the low on a curve. Conversely, winds always blow
away from a high-pressure area. Because of the nature of a low-pressure area, it is usually
associated with warm cloudy weather and rain. Highs are associated with cooler, clear air. When
they move, they create weather fronts.
The Jet Stream
In the middle latitudes is a band of swiftly moving westerly winds called the jet stream. They are
between 6 and 11 km up. In the summer, the jet stream operates about 30-45 degrees. In the
winter, between 15 and 30 degrees. Miami is 27 degrees. The typical jet stream operates at about
300mph and is between 40 and 160km wide. The position of the jet stream is important to pilots
that can use the west to east jetstreams to fly in. The summer ones are much weaker and are not
as effective. At the present, it is thought that the jet stream controls or steers the high pressure
areas on the earth which controls the weather.
Weather Fronts
The boundary or interface between air masses formed by high and low pressure areas are called
weather fronts or just fronts. Storms usually form at the borders of these areas. There are 4
kinds of fronts,
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Cold fronts - cold overtakes warm
Warm fronts - warm overtakes cold
Stationary - nothing is moving
Occluded - a boundary between cold, warm, cool
Cold fronts have dry cool air behind them. The air in front of them is warm and will rise above the
cold air. As the warm air rises, the vapor condenses and clouds form. Sudden temperature changes
and cumulonimbus (storm) clouds form causing thunderstorms. The intensity of the storm is
dependent upon the amount of difference between the warm air and the cold air pressures. High
differences make severe weather. It usually passes quickly and ends with cooler weather.
Warm Front - There is a gentle slope of the air and a slow movement of a warm front. Warm fronts
start out with cirrus clouds and move into stratus clouds with a steady rain. Rain may last for days
but usually one day followed by cloudy warm weather, extremely humid.
Occluded fronts - 2 masses of cold air move into a region occupied by warm moist air. One of the
cold masses overtakes the other and the parcel of warm air is trapped in between the two cold air
masses. Thunderstorms, heavy rains and severe weather are common in occluded fronts.
Thunderstorms
Storms that produce lightning and thunder are called thunderstorms. Warm moist air rises rapidly
into the atmosphere within a cumulonimbus cloud. The water vapor condenses with great speed
causing a thunderhead cloud. When a thunderhead cloud passes over you, you can feel the huge
downdraft of cool air. Large drops of water become small drops of water and the electricity in the
water and air increases but does so at different rates in different parts of the cloud. The
difference in charges causes a lightning bolt to balance off the difference. It can go from one area
of the cloud to another (most common) which is called heat lightning because it gives off about
28,000 degrees, between two clouds or from the cloud to the ground. The heat is so high that the
surrounding air suddenly expands producing a loud noise called thunder. The difference between the
light and thunder is about 5 seconds. You can tell the distance of lightning by counting after the
lightning until you hear it. Divide by 5 and that is the number of miles it is away from you.
Tornadoes
We have no idea what makes a tornado form. When the air is exceedingly moist and lifted at a very
high rate, tornadoes form. Funnels reach to the ground. If over water, it is called a waterspout.
They are not nearly as dangerous as a tornado. It is a small, very powerful storm exceeding
250mph, almost nothing will withstand a class 4 tornado. The tornado has VERY low pressure and
when it passes by a house, the pressure variance causes the house to explode out. About the only
safe place to be is underground. Most tornadoes travel NE with speeds of 55 to 70km. they may
occur anywhere but the usual spots are Kansas, Oklahoma, Missouri and Florida. Suprisingly, very
few people are actually killed in tornadoes. In 1998, central Florida had 39 deaths to tornadoes,
which is very high.
Climatic Changes
Throughout time, wholesale climatic changes have occurred. The earth was warm to the point of
ferns in Canada. Once the earth was overgrown with plants, the Cretaceous period. Once the earth
was ice cold, in glacial periods. Something happened during the Cretaceous period because almost all
of the dinosaurs died out rather quickly, apparently due to rapid cooling of the earth's surface. One
of the theories is that the plates moved a great deal and volcanism put so much dirt and minerals
into the air that it cooled the earth. One theory is that a huge or a series of asteroids or a comet
hit the earth and moved the earth slightly, which caused the reduction. At any rate, we think that
the earth has had between 6 and 12, depending upon whom you read, such climatic disasters. Warm
times on the earth are short and glacial periods are long. We are in a very warm period now. Some
say the sunspots affect the weather every 11 years. Some say it is the moon's change in tilt every
18.6 years, which makes a lot of sense. Milankovitch cycles were first described in the 1920s but
nobody paid much attention to them. The earth's orbit stretches and shortens in a 92,000-year
cycle and the axis of rotation tilts more on a 40,000 year interval. With this information, it is
thought that a 26,000-year cycle shows the earth tilting out of balance and glacial periods occur.
Bands of sedimentary rock in the oceans indicate that this has happened. The 100,000 year old ice
ages seem to back it up too.
New Research
According to much research on Greenland and Europe, the world climate may not be as stable as we
thought. In the last interglacial period 135,000 to 115,000 years ago, it appears that temperatures
flipped suddenly from warm to cold or cold to warm. We believe it is due to high or low levels of
volcanic activity and warm fresh water entered the salt water, creating new currents.