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Air Pollution, Climate Change
and Ozone Depletion
CLIMATE: A BRIEF
INTRODUCTION
 Weather is a local area’s short-term physical
conditions such as temperature and precipitation.
 Climate is a region’s average weather conditions
over a long time.
 Latitude and elevation help determine climate.
 The two most important factors are
temperature and precipitation.
Earth’ climate system distributes heat &
precipitation over time, creating climate
• Creates “weather” – day-to-day winds, clouds, rains, storms,
heat waves, droughts, etc
Earth’s climate system is composed of
atmosphere/ocean interactions (driven by sun)
Masses of air and water transfer solar
energy through circulation/convection
Solar Energy and Global Air
Circulation: Distributing Heat
 Global air circulation is
driven by the uneven
heating of the earth’s
surface by solar energy,
seasonal changes in
temperature and
precipitation:
 Angle of rays
 Surface area
 Reflective surfaces
VERY IMPORTANT: What causes the seasons?
• The ANGLE of the sun’s rays.
• Direct sunlight = summer
• Direct = more sunlight in a smaller area  more
heat stored
• Indirect sunlight = winter
• Indirect = sunlight spread over larger area 
less heat stored
Albedo
 The higher the
albedo of a
surface, the
more sun that is
reflected and
the less heat
stored
 The lower the
albedo of a
surface, the
more sun that is
absorbed and
the more heat
stored.
Core Case Study
Blowing in the Wind:
A Story of Connections
 Wind connects most life
on earth.
 Keeps tropics from being
unbearably hot.
 Prevents rest of world
from freezing.
Figure 5-1
Air Pressure
Definition
Air pressure is pressure exerted by
the weight of Earth’s atmosphere.
At sea level it is equal to 14.69
pounds per square inch.
A barometer is used to measure
atmospheric pressure.
Air Pressure
Pressure Gradient
 Changes from high to
low. On a map there is
an arrow to show this.
A higher pressure
gradient means
stronger winds (the
isobars on a weather
map would be drawn
closer together).
Wind
Cause
 Wind is caused by the pressure
gradient force. High pressure means
more air, and low pressure means less
air. The air moves from high to low,
causing wind.
Wind
The Coriolis Effect
 Forces in the
atmosphere,
created by the
rotation of the
Earth on its axis,
that deflect winds
to the right in the
N. Hemisphere and
to the left in the
S.Hemisphere.
Convection Cells: with No spin
Wind
Coriolis Effect
 Global air
circulation is
affected by the
rotation of the
earth on its
axis.
Figure 5-4
Wind
Friction
 A combination of the pressure gradient
force and the coriolis effect. Friction at
the Earth’s surface causes winds to
turn a little. Friction runs parallel to
the isobar.
Wind
Upper Level Flow
 There is little friction up in the upper
troposphere, driving surface features.
Ex. during big thunderstorms, the
wind in the upper level will tell which
way the thunderstorm will move.
Wind
Cyclones
 (called hurricanes in the Atlantic
and typhoons in the Pacific)
 Violent storms that form over
warm ocean waters and can pass
over coastal land.
 Giant, rotating storms with
winds of at least 74 mph. The
most powerful ones have wind
velocities greater than 155 mph.
Air Masses and Winds
Polar vs. Tropical
 The atmosphere has three prevailing winds.
 Prevailing winds that blow from the North or South
Pole are called Polar Easterlies.
 Winds that blow in the middle lattitudes (between
3o and 60 degrees) are called the Westerlies
 Tropical winds that blow toward the equator are
called Trade Winds.
Prevailing Winds
Air Masses and Storms
Continental vs. Maritime
 Continental fronts are generally cool
and dry, whereas maritime (ocean)
fronts are generally warm and moist.
When these two air masses converge,
the result is usually rain.
Convection Currents
 Global air
circulation is
affected by the
properties of air
water, and land.
Figure 5-5
Convection Cells
 Heat and moisture
are distributed over
the earth’s surface
by vertical
currents, which
form six giant
convection cells at
different latitudes.
Figure 5-6
Circulation Patterns
Hadley Cells
 Warm moist air rises at the equator. Rain
 As air rises, it spreads out north & south, then cools and
sinks at 30 degrees. Dry
 This is why most of the world’s deserts are found at 30
degrees.
 These are called the horse latitudes (3o degrees) because
early settlers would get stuck here in their boats & couldn’t
move. They would finally throw their horses overboard to
lighten the load & get moving again.
 Trade Winds blow towards equator
Circulation Patterns
Ferrell Cells
 Warm air rises at about 60 degrees. Rain
 and sinks at around 30 degrees, dry, both north and
south.
 Westerlies. Predominant winds in US
Circulation Patterns
Polar Cells
 Air rises at about 60
degrees. Rain
 floats north, and
sinks at around 90
degrees, both north
and south. Dry
 Easterlies
Circulation Patterns
Circulation Patterns
Convection Cells
 Ocean water transfers heat to the atmosphere,
especially near the hot equator. (Trade winds)
 This creates convection cells that transport heat
and water from one area to another.
 The resulting convection cells circulate air, heat,
and moisture both vertically and from place-toplace in the troposphere, leading to different
climates & patterns of vegetation.
Sea, Land, Valley, & Mountain
Breezes
 Sea - ocean-to-land breezes that occur during the
day.
 Land - land-to-ocean breezes that occur at night.
 Valley - the wind blows from the plains into a
valley between two mountains, the wind must
divert into a smaller area. This causes high winds
to form through the valleys.
 Mountain - Cool air coming from the top of the
mountain sinks down on the eastern slope,
causing increased winds on the mountain.
Microclimate – Rain shadow effect
 Topography, water bodies and other local features create
local climate conditions known as microclimate.
 For example mountains commonly result in high rainfall on
the windward side and low rainfall in the rain shadow of
the leeward side.
Ocean Currents:
Distributing Heat and Nutrients
 Ocean currents influence climate by distributing heat
from place to place and mixing and distributing
nutrients.
Ocean Currents:
Distributing Heat and Nutrients
 Ocean currents influence climate by
distributing heat from place to place and
mixing and distributing nutrients.
Earth’s Current Climate Zones
Figure 5-2
Weather
Weather is the condition in the
atmosphere at a given place and
time.
Weather includes temperature,
atmospheric pressure,
precipitation, cloudiness,
humidity, and wind.
Local Weather
 Weather is a local area’s short-term physical conditions such as
temperature and precipitation.
 A weather front marks the boundary between two air-masses at
different densities.
 A front is about 100-200 km wide and slopes where warm and
cool air masses collide.
Cold front
Warm front
Weather
Warm & Cold Fronts
 Warm Front - The boundary between an
advancing warm air mass and the cooler one it is
replacing. Because warm air is less dense than
cool air, an advancing warm front will rise up over
a mass of cool air.
 The leading edge of an advancing air mass of cold
air. Because cool air is more dense than warm air,
an advancing cold front stays close to the ground
and wedges underneath less dense, warmer air. A
cold front produces rapidly moving, towering
clouds called thunderheads.
Weather
Stationary & Occluded
Front
 A stationary front is a
transitional zone between
two nearly stationary air
masses of different
density.
 An occluded front is the air
front established when a
cold front occludes
(prevents the passage of) a
warm front.
Seasons
 The Earth’s 23.5 degree incline on its axis remains
the same as it travels around the sun. As the earth
spins around the sun the seasons change.
Earth-Sun-Moon
Earth’s axis has a 23.5° tilt. This tilt always
faces the same way, resulting in seasonal changes
in sunlight and weather.
Solar year: the journey
around the sun takes
365.2425 days.
Earth day: the Earth spins on its
axis with respect to the stars once
every 23h 56 min 4.09s (one
sidereal day). The solar day,
where the sun returns to its
zenith, is exactly 24 hours.
Lunar month: the time between successive
full moons is 29.5 days, but the moons orbit
around the Earth takes 27.3 days. Because
the moon spins on its own axis once every
27.3 days, the same side of the moon always
faces the Earth.
All images: NASA
Orbital Cycles

Three long term cycles that the Earth goes through as it orbits the Sun are:
Axial tilt: the axis of the Earth varies from 21.5° to 24.5°.
Orbital eccentricity: Earth’s orbit varies from almost circular to elliptical.
Precession: the movement of the axes in space causes them to describe a cone.
All images: NASA
Axial Tilt
 The tilt of the Earth’s axis ranges between 21.5° and 24.5°.
 This can have severe effects on the climate.
An axis tilt of 21.5o
allows more heating near
the poles leading to a
less extreme temperature
gradient from pole to
equator.
When tilted at 24.5o the
variation between winter
and summer temperatures
is much more
pronounced.
Eccentricity

When the Earth’s orbit is almost circular (as it is
now), both summers and winters are relatively mild.

This can trigger ice sheet build up as summer is not
warm enough to melt winter snow.
‣
When Earth’s orbit is more elliptical,
summers (as shown here) in the northern
hemisphere can be relatively cold while
winters are relatively warm.
The opposite occurs in the southern
hemisphere
All images: NASA
Precession

Precession alters the orbital position of the summer and winter solstices.
Around 13,000 years ago the southern hemisphere’s summer occurred in June.
Orbital Cycles
 The changes in the tilting
of the Earth’s axis,
combined with
precession and
eccentricity can cause
variations in the amount
of solar radiation
reaching the Earth’s
surface.
 This can trigger the onset
and recession of ice ages.
Formation
of the Atmosphere
 Most of the Earth’s early
atmosphere was lost due
to the vigorous solar
wind from the early Sun.
 Continuous volcanic
eruptions built a new
atmosphere of:
water vapor
carbon dioxide
nitrogen
methane
The Atmosphere
 The mixture of gases known as
air, protects life on Earth by
absorbing ultraviolet radiation
and reducing temperature
extremes between day and
night.
 The atmosphere is not static.
Interactions involving the
amount of sunlight, the spin of
the planet and tilt of the Earth’s
axis cause ever changing
atmospheric conditions.
Weather occurs in the troposphere. Gaseous water molecules
held together by intermolecular forces cause the formation of
clouds.
The auroras occur in the thermosphere and are caused by
interactions between the Earth’s atmosphere and charged
particles streaming from the Sun.
Air Density
 The atmosphere
consists of several
layers with
different
temperatures,
pressures, and
compositions.
STRUCTURE AND SCIENCE
 The atmosphere’s innermost layer
(troposphere) is made up mostly of
nitrogen and oxygen, with smaller
amounts of water vapor and CO2.
 Ozone in the atmosphere’s second layer
(stratosphere) filters out most of the
sun’s UV radiation that is harmful to us
and most other species.
The Atmosphere
 Earth's atmosphere contains roughly:
78% nitrogen
20.95% oxygen
0.93% argon
0.038% carbon
dioxide
Trace gases
The Earth’s atmosphere (where pressure becomes negligible)
is over 140 km thick. Compared to the bulk of the planet, this is
an extremely thin barrier between the hospitable and the
inhospitable.
1% water vapour
All images: NASA
Troposphere
 75% of mass of atmosphere
 0 to 11 miles in altitude
 78% nitrogen, 21% oxygen
 Location of Earth’s weather
 Temperature decreases
with altitude until the next
layer is reached, where
there is a sudden rise in
temperature
Stratosphere
 11 miles to 30 miles in altitude, calm
 Temperature increases with altitude
 Contains 1000x the ozone of the rest of
the atmosphere; ozone forms in an
equilibrium reaction when oxygen is
converted to O3 by lightning and/or
sunlight
 99% of ultraviolet radiation (especially
UV-B) is absorbed by the stratosphere
Mesosphere & Thermosphere
 Mesosphere
 30 to 50 miles in
altitude
 Temperature
decreases with
increasing
altitude
 Thermosphere
 50 to 75 miles in
altitude
 Temperature
increases with
increasing
altitude
 Very high
temperatures
Composition of the Atmosphere
 Components –Nitrogen 78%, Oxygen
21%, .93% argon, & .038% carbon
 Layers – troposphere, stratosphere,
mesosphere, thermosphere, exosphere
(extends from 310 miles to
interplanetary space)
Heat Transfer
 Conduction
 Warm air holds more moisture than cold air.
During conduction, heat & moisture from the
ocean or land moves into the atmosphere.
 Ex. cold air moving over warm water (like a lake),
forming steam fog.
 Radiation
 Radiation drives weather. Heat from the sun
warms the earth, which radiates the heat back
into the atmosphere.
 Convection
 Air & water movement
Natural Greenhouse Effect
 Some of the solar energy is trapped by molecules of
greenhouse gases (water vapor, carbon dioxide,
methane). Otherwise earth would be much colder
Coriolis Effect
 The spinning of the
earth creates
 Different wind speeds at
different latitudes (faster
at equator, slower at
poles)
 clockwise winds in the
northern hemisphere
 counter clockwise winds
in the southern
hemisphere
N. hemisphere
CLOCKWISE
 This movement is called
the Coriolis Effect.
 Watch:
https://www.classzone.com/bo
oks/earth_science/terc/content/
visualizations/es1904/es1904pa
ge01.cfm?chapter_no=visualiza
tion
S. hemisphere COUNTER -
Coriolis and Convection cells
Without the Coriolis Effect, air would
travel in two large cells. The warm air
at the equator would rise and move
toward the poles. As it moved to the
poles, it would cool and sink, then
move back to the equator along land,
warming as it moved.
With the Coriolis Effect, air still travels
from the equator toward the poles, but
due to the wind patterns, the 2 cells are
broken into 6 global cells. Warm air
rises in each cell and cools as it travels
through the atmosphere, then sinks and
warms as it travels across the land.
Climate Changes with Latitude
 Starting at the equator
and moving to the
poles it generally:
 gets colder and drier
There are exceptions
particularly for rainfall!
Biomes – observe latitude similarities
Climate Changes with
Elevation/Altitude
 As you go up in elevation:
 Less soil and less
nutrients  less plants
 Less oxygen
 lower air pressure 
thinner atmosphere 
less organisms
 Temperatures decreases
 More UV rays –
plant growth
limits
Ocean Currents: Transport nutrients and heat
all over the globe Also called the Ocean Conveyor belt

Driven mostly by:



Wind/Coriolis
Temperature gradients (colder water sinks) THERMO
Salinity gradients (saltier water sinks) HALINE
Upwelling
 Occur when ocean currents
pull water from the deep
ocean up to the surface
 Upwellings pull cold,
nutrient rich water up to
the surface
 Good for fishing: increases
NPP as nutrients are often
a limiting factor
Gyres
• Direction driven by the Coriolis Effect and the
continents
• 5 gyres that spin clockwise in the N. hemisphere and
counter clockwise in the S. hemisphere
• Redistribute heat and nutrients
Ocean Currents
 There are two types of Ocean Currents:
1. Surface Currents / Surface Circulation
 These waters make up about 10% of all the water in the
ocean.
 These waters are the upper 400 meters of the ocean.
 Driven mostly by wind
2. Deep Water Currents
 These waters make up the other 90% of the ocean
 move around the ocean basins by density and gravity.
 The density difference is a function of different temperatures
and salinity
 These deep waters sink into the deep ocean basins at
high latitudes where the temperatures are cold enough
to cause the density to increase.
El Nino Southern Oscillation
El Nino Southern
Oscillation (ENSO):
periodic weather
pattern in the Pacific
ENSO effects – El Nino
 During an El Nino event
 Warmer ocean temps in
the Pacific
 Warmer and wetter in the
western Americas from
So. Cal south (Warmer and
dryer in the Northwest US
during winter and warmer
and wetter in the summer)
 Suppresses hurricane
activity in the Atlantic
ocean
 Major declining in fishing
populations during an El
Nino
 Drought in the western
Pacific and Australia
ENSO effects – La Nina
 During a La Nina event
 Pacific ocean temps are
colder than normal
 Droughts along the west
coast of the Americas
(more snow in northwest
US)
 Active hurricane season
in the Atlantic
 More rain in the Western
Pacific and Australia