Download Atmospheric pressure

Chapter 22.1
Characteristics of the
Atmosphere
What is the Atmosphere?
 Atmosphere
– the layer of gases that surrounds the
Earth.
The Two Functions of Our Atmosphere:
1. To protect the Earth’s surface from the Sun’s radiation.
2. To regulate the temperature of the Earth’s surface.
Chemical Composition of the
Atmosphere
Abundant Elements
 Nitrogen
 Oxygen
 Argon
Abundant Compounds
(More than one element)
 Carbon dioxide (CO2)
 Water Vapor (H2O)
Other Components
 Dust
 Pollen
Nitrogen in the Atmosphere
 Nitrogen leaves the atmosphere and enters the soil where it
is “fixed” into usable compounds by nitrogen fixing bacteria in
the soil and on the roots of plants called legumes (ex.
soybeans and peanuts).
 Nitrogen compounds are returned to the soil through animal
waste and the decay of dead organisms.
 Nitrogen is released back into the atmosphere by the decay
of dead organisms.
Nitrogen makes up
78% of the Earth’s
atmosphere.
Oxygen in the Atmosphere
Oxygen makes up 21% of the Earth’s atmosphere.
Ways That Oxygen is Taken Out of the Air:
1. The “life processes” of animals, bacteria, and plants (i.e.
3.
Respiration)
2. Burning (ex. forest fires, fossil fuels)
The weathering of certain kinds of rock (and soil …
especially those rich in iron i.e. Oxidation)
Processes That Put Oxygen Into the Air:
1. Photosynthesis
Respiration
Photosynthesis
Photosynthesis and Respiration:
In Simple Terms
It should be noted that almost all living things, including
plants, undergo aerobic respiration.
 Respiration – the process whereby oxygen (O2) is used to release the
energy stored in food, producing carbon dioxide (CO2) and water
vapor (H2O).
 Photosynthesis – the process whereby green plants, algae, and
certain protests use sunlight, carbon dioxide (CO2), and water vapor
(H2O) to produce food and oxygen (O2).
Photosynthesis
and
Respiration:
Inside the Cell
The Oxygen-Carbon Dioxide Cycle Part 1
The Oxygen-Carbon Dioxide Cycle Part 2
Water Vapor in the Atmosphere
The Two Process That Put Water Vapor Into Air Are:
1. Evaporation
2. Transpiration (from plants)
The Two Process That Take Water Vapor Out of Air Are:
1. Condensation
2. Precipitation
Based on the time of day,
location, and season,
water vapor in the
atmosphere can vary from
as low as 1% to as much
as 4%.
Ozone: Important Substance in the
Atmosphere
Ozone (O3) is a form of
oxygen found in the
stratosphere.
Before Earth had an ozone layer,
all life lived under the oceans …
NONE could live above them!
Ozone absorbs harmful
ultraviolet radiation (UV rays)
coming from the sun.
Ultraviolet radiation can cause
severe burns, cancers, mutations,
and even death!).
Ozone can be destroyed by:
CFC propellants in old aerosol
spray cans, Freon coolant from
refrigerants in old refrigerators
and air conditioners, and nitrogen
oxide exhaust gases from burning
supersonic aircraft fuel.
Ozone: a Little Chemistry
Ozone is created when ultraviolet radiation (UV rays) from
the Sun strikes and splits oxygen molecules (O2) to atomic
oxygen (O).
The atomic oxygen (O) quickly combines with further
oxygen molecules to form ozone (O3):
O2 + light
->
O + O2 ->
O + O
(1)
O3
(2)
It should be noted that ground level ozone, which is produced
by hydrocarbons that react with sunlight, is a pollutant itself.
Ground level ozone causes SERIOUS lung irritation!!!
Dust In The Wind…
 Particulates – tiny solid particles in the air.
Sources of Atmospheric
Particulates:
 Dust from volcanic
eruptions
 Ash from fires
 Microscopic organisms
 Minerals lifted from soil
by winds
 Pollen from plants
 Particles from meteorite
impacts
 Salt from sea spray
The tinier the particle, the
longer it can stay suspended in
the air.
What is Atmospheric Pressure?
Atmospheric pressure – the force per unit area
that is exerted on a surface by the weight of
the atmosphere.
99% of the mass of the atmosphere is located within 32 km (20
miles) of the Earth’s surface.
The general trend between atmospheric pressure and altitude is
that, the higher up in the atmosphere one goes, the less
atmospheric pressure there will be.
altitude pressure
A you go up in the atmosphere, the air gets thinner and therefore there is less
pressure. That is why ears pop when ascending and descending in an airplane!
Measuring Atmospheric Pressure
Measuring atmospheric pressure:
 Barometer – a device used to measure atmospheric pressure.
There are two types of barometers:
 Mercury Barometer – a barometer that works when air pushes down
on a pan of mercury forcing the mercury to rise up a calibrated,
inverted tube.
 Aneroid Barometer – a barometer that works when air pressure
squeezes on the sides of a can moving an attached pointer.
Standard air pressure at sea
level can be expressed as one
atmosphere, 760 mm of
mercury, or 1000 mb.
Since air pressure decreases
with increasing altitude, an
aneroid barometer can be
calibrated to read altitude.
However, to function
accurately, altimeters must be
kept calibrated for local
weather conditions.
Layers of the Atmosphere 1
Did you know…
Mount Everest,
the highest
elevation above
sea level, is only
about 8.8 km
high, keeping it in
the bottom layer
of the
atmosphere.
The Earth's atmosphere is composed of several layers:
We live in the Troposphere where almost all weather occurs
(ex. wind, clouds, fog, rain, hail, sleet, snow and storms).
Above the Troposphere is the Stratosphere, which contains the Ozone Layer,
which blocks out harmful UV rays.
Commercial airliners (ex. a 747) usually fly in the troposphere, whereas
supersonic jet airliners (ex. the Concorde) fly in the lower stratosphere.
Layers of the Atmosphere 2
Thermosphere
 Lower region called ionosphere.
 Upper region called exosphere.
 Nitrogen and oxygen atoms absorb
deadly gamma and X rays here, explaining
the unexpected increase in temperature.
Mesosphere
 Coldest layer of the atmosphere.
Temperature within this layer decreases
as altitude increases.
Stratosphere
The Ozone Layer absorbs harmful UV
Rays here, explaining the unexpected
increase in temperature.
Troposphere
All weather change occurs here.
 Temperature within this layer
decreases as altitude increases because
there is an increase in distance from the
warming effect of sunlight absorbed by
the Earth’s surface.

Air Pollution … aka Smog
The greatest source of air pollution today is from the burning
of fossil fuels which releases pollutants such as sulfur dioxide
gas (SO2), hydrocarbons, nitrogen oxides (NO), carbon monoxide
(CO), and lead (Pb) into the air.
 Temperature inversion – a condition in which a layer of colder,
polluted air is trapped below warm air and when then cannot
disperse causing smog to form.
Rain Gone Bad … Acid Rain!!!
All rain is somewhat naturally acidic!!
But when chemicals from car and factory exhaust (CO, CO2, NO, NO2,
SO, SO2) combine with rainwater, they can produce HIGHLY acidic
rains that damage buildings and monuments and kill plants and fish.
Who is a Meteorologist?
A meteorologist studies all characteristics of the
atmosphere, weather, and climate.
Meteorologists can specialize in areas such as agriculture,
aviation, forestry, or health.
http://www.nws.noaa.gov/
http://66.208.12.20/amsedu/dstreme/
http://www.weather.com/index.html
http://www.wqad.com/
http://www.kwqc.com/
Weather vs. Climate


Weather – the general condition of the atmosphere at a
particular time and place
(i.e. temperature, air movements, and air moisture).
Climate – general weather conditions over many years.
The End!...
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