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Unit 6 Chapter 19The Atmosphere
Meteorology – _______________________________
Meteorologist – ______________________________
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Section 1 Characteristics of the Atmosphere
The atmosphere is the gaseous layer that surrounds the Earth. It is
made up of chemical elements that protect the earth from
the sun’s radiation while providing us with a climate that
will sustain life.
Composition of the Atmosphere:
See page 1 ESRT
Remember:
Early atmosphere came from the volcanoes
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Then sunlight split the water molecules into
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Then photosynthesis kicked in.
Today our Air is:
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The % of Nitrogen and Oxygen stays constant up to 80km
Nitrogen in the Atmosphere
Nitrogen makes up about ________ of the Earth’s Atmosphere.
Nitrogen is added to and removed from the Atmosphere
through the nitrogen cycle (chpt 2).
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Oxygen in the Atmosphere
Oxygen makes up about 21% of the Earth’s Atmosphere. O2 is
added to and removed from the Atmosphere through the
Oxygen Cycle (chpt 2).
Plants take in CO2 release O2
Animals take in O2 release CO2
Plants decompose to CO2
H2OV is released in evapotranspiration & exhaling
Water leaves by way of precipitation
This stays in a semi-balance. However the levels of CO2 maybe on
the rise according to the Mauna Loa Observatory in Hawaii which has
been monitoring it from 1959 – Present.
Water Vapor in the Atmosphere
Water Vapor (H2O(v), H20(gas)) is present in most air but the percent
changes constantly. It is highest near the surface and then lower as
you go up in altitude.
Dry Air has less than 1% water vapor which in turn has a higher
pressure reading.
Moist Air has approximately 4% water vapor which has a lower
pressure reading.
The more water vapor in the atmosphere, the lower the pressure is.
Water weighs less than oxygen, therefore, the more water in the air,
the lower the pressure.
Ozone in the Atmosphere
Ozone (O3) in the upper atmosphere absorbs harmful UV Rays.
_________________________ – reduce the ozone in the air
therefore increase the ultraviolet light reaching the surface
(us). CFC’s can come from coolants, foam products and
cleaning supplies for electronic components.
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Particulates in the Atmosphere
The most common particulates are
Volcanic Ash, dirt/dust, pollen and salt from sea spray.
Others are:
________________________:
An Air borne gas or particle that occurs at a concentration
that is capable of harming humans.
In 1970 the Clean Air Act was passed. It tried to limit the
amounts of CO, NO2, SO2, particulate matter, pb (lead)
and O3 that were being released into the atmosphere.
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SO2 or Nitrogen Oxides react with water causing the levels of
acid in the precipitation to rise. Acid is measured on the pH
scale.
pH scale: 10 times more acidic than the number before. The lower
the pH number the more acidic the rain is.
Can do more harm than anyone thinks. It is harmful to lakes,
streams and forests. It will roughen surfaces and remove the
delicate carved details.
_________________________
The term was made in the early 1900’s. It refers to the smoky
fog in London. Now it means the photochemical smog.
Because smog is so thick it can create weather conditions that
are very unique, one is temperature inversion.
Atmospheric Pressure
Gravity holds the gases down, the molecules get compressed and
exert a force on the Earth’s surface. The pressure
exerted is called the atmospheric pressure. It is exerted
equally in all directions.
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We say “light as air” but air is not really light. From the top of the
atmosphere to sea level it is approximately ___________ pounds per
square inch (yep this is on top of you too).
Think about this, when you stretch your hand out palm up, we don’t
even think about any pressure being on it. We don’t feel it,
therefore, we don’t think it’s there. We have pressure pushing down
on our hand, while pressure is pushing up and out. This keeps us in
balance so we can perform our daily stuff. An astronaut and
submariner need to pressurize their environment to be the same as
normal.
Pressure decreases as elevation increases. Air pressure decreases
about 50 percent for every 5 km increase in elevation.
Mile High Stadium (Denver) is 1.6 km above sea level; pressure
is about 82% than at sea level (approx 18% decrease).
Measuring Atmospheric Pressure
Meteorologists use 3 units to measure pressure: atmospheres (atm),
millimeters or inches of mercury and millibars (mb).
___________________________
_____________________The more air pressure the higher the Hg moves up the tube
lower air pressures allow the Hg level to drop
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An aneroid barometer uses a metal capsule to measure the pressure
changes. It operates in the same manner as a seismograph.
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Layers of the Atmosphere
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Lowest Level of the Atmosphere
Contains approx 80% of the total mass
All weather occurs in this layer (water vapor)
Most small jets fly in this layer
Temperature decreases as you increase altitude.
Most air temperature decrease approx. 6.5OC per km
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The interchange between the troposphere &
stratosphere
At equator it is approximately 16km
At the poles it is approximately 9km
The jet stream is located just below the pause.
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Height of approx 50km
No water in this layer so it is clear & dry
About as cold as the tropopause- but warms as
you go up.
Contains ozone layer which absorbs UV Light
Large jets fly here
Strong steady winds
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The boundary between the stratosphere and mesosphere
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Between 50 – 90 km
Temperatures drop as you increase altitude
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The boundary between the upper mesosphere and
thermosphere
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About 90km
Atmosphere is extremely thin
Temperature can rise to about 1000oC
Separated into layers of gases
Heavier – lower (nitrogen)
Middle – Oxygen at approx 1000km
Higher – lighter (Helium) approx 2400km
Highest – lightest (Hydrogen)
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A layer of the atmosphere containing Ions (Charged atoms)
The ions are deflected by the magnetic field to the North and
South Poles. They interact with air molecules to form
auras.
Radio waves are reflected in this layer causing waves to travel
further when the solar flares occur. TV waves need to be
captured by satellite and bounced back to earth.
__________________________
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It is the last layer of the atmosphere, truly outer space.
Temperature Inversion
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Normally as altitude increases, temperature decreases. In a
temperature inversion the temperature at the surface is
cooler than at higher altitudes. On clear dry nights – the
surface and air just above the surface cools quickly. The
land cools faster than the air which cools the air even more
up to a few hundred meters. Cool or cold air is denser than
warm air so this air can get trapped under warm air. This
can trap pollution in the air near the surface and cause
health problems. Strong winds or strong sunlight can destroy
temperature inversions.
Section 2 Solar Energy and the Atmosphere
The Earth is heated by the transfer of energy from the sun either
directly or indirectly.
Heat energy enters and moves through the atmosphere in 3 ways:
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Radiation is the transfer of energy in the form of visible light, ultra
violet rays and other forms of electromagnetic energy. It does not
require a medium, making it the only way energy can travel through
space.
Electromagnetic Spectrum:
The Atmosphere and Solar Radiation
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Sunlight
Source of most heat on the earth and in the air
As long as heat budget is in balance, earth is OK. Out
of balance: It can either heat up (Global
Warming**), or cool down (Ice Age).
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Clouds, dust, water droplets and gas disrupt the path of the
radiation. The scattering makes the sky appear blue during the day
and red at sunset.
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The amount of sunlight (solar energy) can either be absorbed or
reflected. The characteristics of the area will determine whether it is
reflected or absorbed.
Albedo
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___________________________. Because 30% of the insolation is
already reflected, we are considered a 0.3 albedo.
Absorption and Infrared Energy
The sun’s energy that reaches us is absorbed by rocks, soil, water
and other surface materials. The short wavelengths (infrared and
visible light) heats up the surface when the surface absorbs the
radiation. It then re-emits the energy at longer wavelengths. Gas
and water vapor absorbs these rays which heats up the lower
atmospheric layers. This keeps the Earth nice and warm.
It can bend the light rays and produce a ________________ too.
The Greenhouse Effect
The greenhouse effect occurs when infrared radiation remains in
Earth’s atmosphere. Usually insolation has short wavelengths; it can
easily pass through the atmosphere, infrared radiation has longer
wavelengths and cannot leave the atmosphere as easily. This
creates a situation that will keep re-heating the atmosphere, bringing
the temperatures up.
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Human Impact on the Greenhouse Effect
Water and Carbon Dioxide easily trap infrared radiation. (H20 and
CO2 are greenhouse gases)
Burning fossil fuels release C02 and H20 may be increasing the
greenhouse effect.
Actually the greenhouse effect is keeping the planet at a habitable
temperature right now.
Variations in Temperature
The intensity of the sun varies with the time of day, latitude and
season (time of year). Certain materials also affect the intensity.
Time of Day:
As we know the sun is at it’s highest at solar noon. This allows
for the most intense rays of the sun to be radiated to us.
The warmest part of the day is 1 – 2 hrs after solar noon. Why?
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So the coldest part of the day is just before sunrise
Why?
Latitude and the Seasons
Latitude is the primary factor that affects the amount of solar energy.
When the amount of sunlight changes on each location, different
portions will experience different seasons.
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At ___________ the sun warms the earth the most
At ____ the sun warms the earth the least plus the sunlight has to go
through more atmosphere
Equator – warm – sun high in the sky
Poles – cool – sun low in the sky
Long Island – warm summer – sun high in the sky:
Cool winter – sun low in the sky
The sun is the highest in the sky on __________ in the Northern
Hemisphere. The warmest time is ____________. The sun is the
lowest in the sky on ____________ in the Northern Hemisphere.
The coldest time is in _____________________.
Water in the Air and on the Surface
Cloud Cover:
More insolation is available on clear days then on cloudy days
because it is reflected back into the atmosphere.
Heating of Water and Land:
Land heats up faster and higher than water
Land cools down faster and lower than water
Land near the oceans does not warm up as much or cools down as
much as land locked areas
Dark rough
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Light smooth
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Land
Low specific heat
Heats up quick
Cools down quick
Sunlight penetrates
Surface only
Heat only moves by
Ocean
High specific heat
Heats up slowly
Cools down slowly
Sunlight penetrates
many feet
Heat moves by
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Conduction
conduction and
convection
Conduction
___________________________ It is actually the transfer of energy
through the collision of the atoms or molecules of a substance.
Ex. Pot on the stove: Air touching warm ground.
Convection
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Ex. The water in the pot boiling.
Section 3 Atmospheric Circulation
Air near the surface generally flows from the poles towards the
equator. This is because air flows from high pressure (cold) to low
pressure (warm).
High Pressure-_________________________________
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-___________________________________
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Low Pressure-__________________________________
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- ___________________________________
The Coriolis Effect
. Northern Hemisphere
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Southern Hemisphere
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B.
A.
B.
C.
Greater near the poles
Greater on faster moving objects than slower ones.
Does not depend on movement or direction.
Noticeable for objects (rockets, airplanes, etc) traveling over
great distances and at great speeds. Also true for wind and
water currents.
Because of the Coriolis Effect and the fact that pressure goes from
High to Low creating the wind, it gives us the direction of winds in a
High or Low.
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The winds are affected by friction between the air and the ground.
Friction reduces the impact of the Coriolis Effect and the surface
winds. The smoother the surface, the faster the winds, the stronger
the Coriolis Effect will be.
Higher altitude winds are not affected by the friction. At heights
about 2km the Coriolis Effect is great. This curves the winds in a
High or Low pressure.
http://www.classzone.com/books/earth_science/terc/content/visualiz
ations/es1904/es1904page01.cfm?chapter_no=visualization
Global Wind Patterns
Some winds are predictable, while most are affected by other
variables.
Ex. Temp differences, time of year, topography
Without the coriolis effect the winds would only shift seasonally
warm air rises to polar regions in summer. Cold air moves
towards the equator in winter. This would produce one circular
cell in each hemisphere.
Three-celled circulation model:
The most popular model- takes into consideration the coriolis
effect.
Both Hemispheres have 3 cells
Equator 0o – 30o
30o - 60o
60o - 90o
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Caused by alternating bands of high and low pressure
60o – Polar Front – cold air moves down, warm up
30o – flows back to equator because it is high
Air blowing from the Poles is deflected to the right
90o – 60o - Easterlies
60o - 30o - Westerlies
30o - 0o - Easterlies
In the Southern Hemisphere it is reversed.
Trade Winds
Occur between Oo and 30o north or south. In the Northern
Hemisphere they flow from the Northeast. In the Southern
Hemisphere they flow from the Southeast. They were used in the
18th and 19th century for trade ships.
Westerlies
Occur between 60o and 30o. In the Northern Hemisphere they flow
from the southwest. In the Southern Hemisphere, they flow from the
Northwest. They blow throughout the contiguous United States.
Polar Easterlies
Occurs at 60o North or South of the equator. It is a zone of low
pressure. The winds are the strongest where they flow off of
Antarctica.
The Doldrums and Horse Latitudes
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The Doldrums are also known as the Inter-Tropical Convergence
Zone. It is a low pressure zone at the surface in the tropics due to
heating. It is a place where both hemispheres converge.
It is Hot & Humid; has little to no wind; rain is common
The Horse Latitudes are between 20o and 30o, occurs when
sinking air forms a subtropical high pressure zone. Little to no
precipitation; most of the deserts are located within this zone.
Wind Pressure Shifts
This occurs because of the shift in the position of the sun during the
seasonal changes. Different areas receive different amounts of
heating, which causes the shift in wind patterns. Some areas that
usually have Westerlies in the winter may experience a trade wind in
the summer.
Jet Stream
The jet stream is narrow bands of swift moving winds that blow in
the upper troposphere and lower stratosphere. They blow from the
West to the East in North America (West Winds). They can reach
speeds of approximately 400 km/h. Typically 100’s of km wide and
approx 2 – 3 km thick. They push cold dry air down from Canada in
the winter – Polar Jet Stream. They push warm moist air up from the
Gulf region in the summer (subtropical, does not change speed or
position). Not continuous around the globe.
Local Winds
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These are winds that are not part of the global wind belt. They are
influenced by local conditions and temperatures.
A breeze is any wind that is less than 50 km/h.
Land and Sea Breezes
During the day land heats up and causes a low pressure
area. The water is colder (high pressure area) so air will
rush from high to low pressure, creating a wind.
At night the opposite occurs. The water will retain heat
longer so it becomes the low pressure and the land loses
heat quicker becoming the high pressure. Wind will rush
from the land to the sea.
Mountain and Valley Breezes
During the day the air blows up hill because it is cooler in
the valley, the sun warms the hill first. At night the colder
air blows down slope.