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ATMOSPHERE
Atmospheric Basics
ATMOSPHERIC BASICS
 99% of Atmosphere
composed of
NITROGEN and
OXYGEN
 1% composed of
Argon, Hydrogen,
Carbon Dioxide, Water
Vapor, and other gases
ATMOSPHERIC BASICS
 Key Atmospheric Gases:
– Amount of water vapor (humidity) in air changes
constantly
 Depends on seasons
– Carbon Dioxide and water vapor regulates the
amount of energy the atmosphere absorbs
– Water can be found as solid, liquid, and gas
– Solids such as dust and salt also found
ATMOSPHERIC BASICS
 Reach out and grab a
handful of air!
 What are you holding
right now?
 Argon, Oxygen,
Nitrogen, Water Vapor,
Carbon Dioxide, and
minute amounts of
dust and salt!
ATMOSPHERIC BASICS
 OZONE:
– Gas formed by the addition of a third oxygen
atom in an oxygen molecule
– Exists in small quantities
– Absorbs ultraviolet radiation from Sun
– Keeps us from burning our skin constantly
– Ozone layer is thinning over time
– LET’S LEARN SOME MORE!
ATMOSPHERIC BASICS
ATMOSPHERIC BASICS
 Structure of the Atmosphere:
– Atmosphere made up of
several layers:
 Troposphere
 Stratosphere
 Mesosphere
 Thermosphere
 Exosphere
– Each layer differs in
composition and temperature
ATMOSPHERIC BASICS
 Lower Atmospheric Layers:
– Troposphere:
 Layer closest to Earth’s Surface
 Where weather occurs and pollution
accumulates
 General decrease in temperature from
bottom to top
 Upper limit/boundary: TROPOPAUSE
– Located 9-16 km above Earth’s surface
ATMOSPHERIC BASICS
 Lower Atmospheric Layers:
– Stratosphere
 Made up primarily of concentrated ozone
– Ozone: O3
 absorbs UV radiation and heats
stratosphere
 Increasing temperatures until the
STRATOPAUSE
– STRATOPAUSE: separates Mesosphere and
Stratosphere
– Located 50 km above Earth’s surface
 Planes fly in Stratosphere to avoid storms
ATMOSPHERIC BASICS
 Upper Atmospheric Layers:
– Mesosphere:
 Has no concentrated Ozone
 Located 50 miles above sea level
 Decreasing temperatures to -800C—ice
crystals can form
 Very thin air so hard to breathe
 MESOPAUSE: boundary between
Mesosphere and Thermosphere
ATMOSPHERIC BASICS
 Upper Atmospheric Layers:
– Thermosphere:
 Extends to beginning of outer space
 Contains very little of atmosphere’s mass
 Increasing Temperatures more than
10000C
 Wide spread molecules—air does not seem
as warm to humans
 Contains Ionosphere = electrically charged
particles and progressively lighter gases
ATMOSPHERIC BASICS
 Upper Atmospheric Layers:
– Exosphere:
 Outermost layer of Earth’s atmosphere
 Beyond Exosphere lies Outer Space
 5,500 miles from Earth
 No weather occurs in Exosphere
ATMOSPHERIC BASICS
 Solar Fundamentals:
– Radiation: the transfer of energy
through space by visible light, UV
light, and other forms of
electromagnetic waves.
 Causes us to feel warm from Sun
 Earth absorbs and sends back
radiation into space
 Any substance that has temperature
above Absolute 0, gives off radiation
ATMOSPHERIC BASICS
ATMOSPHERIC BASICS
 Solar Fundamentals:
– Earth reflects 35% of incoming solar radiation
– 15% is absorbed by atmosphere
– 50% is absorbed directly or indirectly by Earth’s
surface
– Different areas absorb more/less radiation than
others
 Water heats and cools more slowly than land
 Darker objects absorb energy faster than lighter ones
ATMOSPHERIC BASICS
ATMOSPHERIC BASICS
 Solar Fundamentals:
– Conduction: transfer of energy that occurs
when molecules collide
 Energy radiated by Earth warms atmosphere
– Boiling water in pot
ATMOSPHERIC BASICS
ATMOSPHERIC BASICS
 Solar Fundamentals:
– Convection: the transfer of
energy by the flow of a heated
substance
 Pockets of air near Earth’s
surface are heated, become
less dense than surrounding air,
and rise.
 As warm air rises, it expands
and begins to cool
 When cools, becomes more
dense and sinks
ATMOSPHERIC BASICS
Why Do We Have
Weather?
An Introduction
Take good notes! There will be a
quiz at the end of this
presentation.
THE CAUSES OF WEATHER
 Meteorology = study of atmospheric
phenomena
– “Meteor” = “high in the air”
THE CAUSES OF WEATHER
 Weather & Climate:
– Weather = current state of the atmosphere
 Short term variations
– Climate = long-term variations in weather for a
particular area
 Usually averaged over 30 years
WHY DO WE HAVE THE
WEATHER ?
 Just think about it!
 Why is there wind? Why does it blow
from one direction one day and another
the next?
 Why is it rainy one day and dry the next?
 How come it’s cold in the winter?
 How can we have hail in the summer?
 What causes snow and freezing rain?
Let’s take a look at the weather
picture and why we have weather!
If we were to pick one term to help
explain why we have weather, what do
you think would be a good word?
You might pick heat or sun….but another
good choice would be
Convection
Convection is the transfer of heat,
usually in gases or liquids.
After the atmosphere is warmed by radiation and
conduction, the heat is transferred throughout
the atmosphere by convection.
 Since warmed air has
more space between the
molecules, it’s less dense
and rises
 Cooled air is more dense
and tends to sink
 In general, air near the
equator tends to rise and
air near the poles tends
to sink
Take a look at this!
Notice the band of clouds
around the equator ?
This is the ITCZ or
Inter Tropical Convergence Zone
Why do you think there is this
band of clouds near the equator?
Did you figure it out?
 Warm, moist air in the topics rises
 Cold air can hold less moisture than warm
air
 As the moist air rises, it condenses and
forms clouds!
More on this later
Consequences of Rotation: the
Coriolis effect
The Weather Highways
 The rotation of the earth
creates the Coriolis
effect.
 The Coriolis effect
causes the air and water
to be deflected to the
right north of the
equator.
 This creates global
weather highways
The Westerlies
 Because of our latitude,
most of our weather
comes from the west
 Looking at the weather
map, what type of
weather might we
expect?
 What type of weather
might we expect in a few
days?
Let’s break for a short review
1.Transfer of heat in liquids or gases_____
2. _____ air is dense and tends to sink.
3. Band of clouds found around the
equator______
4. Cold air holds _____ moisture than warm
air
5. The Coriolis effect causes the air and
water to be deflected to the _____ of
the equator
How did you do?
1. CONVECTION
2. COLD
3. ITCZ
4. LESS
5. RIGHT