The Earth’s Atmosphere
Chapter Two
APES
Homework Atmosphere
Answers
1=1
7=3
13=2
19=2
25=2
2=3
8=5
14=3
20=2
26=5
3=2
9=3
15=4
21=2
27=3
4=5
10=4
16=3
22=5
28=5
5=5
11=5
17=4
23=4
29=5
6=2
12=1
18=2
24=2
30=4
Solar Energy as Radiation
Nearly 150 million kilometers (93,000,000 miles) separate the sun and
earth, yet solar radiation drives earth's weather.
What is Weather?
Weather is the mix of events that
happen each day in our atmosphere
Weather
Weather is comprised of the
elements of:
a) air temperature
b) air pressure
c) humidity
d) clouds
e) precipitation
f) visibility
g) Wind
.
Convection Currents
Convection currents happen when the sea is warmer than the
lands, and so the hot air rising from the sea flows to the cold air
over the land (as heat moves to cold) which forces the cold air to
go up and fill the space the hot air has left. This works the other
way round in the day as the land is hotter, and so the hot air
form the land flows over to the cold air over the sea.
Polar Cell…Begin at
polar latitudes 90 to
60 degrees latitude
Ferrel Cell…30 to 60
degree latitude
Hadley cell…Begins
near the equator 0 to
30 degrees latitude
Note both north & south
Latitudes have these
circulation patterns
Hurricanes are strong wind
storms, which are cyclonic in
nature. This means that they
revolve around a central point,
which is known as an 'eye'. The
eye is the calmest part in the
storm, while the winds raging
around the storm have reached
a speed of 250 km an hour
(156mph)! Winds at this speed
classify the hurricane as a
category 5. The winds rotate in
an anti-clockwise direction in
the northern hemisphere, and
in a clockwise direction in the
southern hemisphere.
 Hurricanes are formed in
tropical, ocean areas. The
warm air above the ocean
begins to rise, and as it rises,
it condenses and forms clouds
and rain droplets. The process
of condensation always
results in the release of heat.
What is the
Coriolis Effect
The force due to the
Earth's rotation that
cause objects in
motion to veer to the
right in the Northern
Hemisphere and to
the left in the
Southern
Hemisphere.
Far more violent than hurricanes are
tornadoes. Winds surrounding
tornadoes often reach speeds of 100
miles an hour, and have even
reached speeds of 300 miles an hour.
 Tornadoes are usually formed
from thunderstorms and can
be defined as a violent column
of air extending from the base
of a thundercloud to the
ground. To put it simply,
thunderstorms that rage in
the sky 'drop' what appears to
be a rope, but is actually a
gust of wind moving in a
circular direction. When this
'rope' touches the ground, it
wreaks havoc.
Earth's Atmosphere
Thin Gaseous envelope
99% of atmospheric gases, including water vapor, extend only 30
kilometer (km) (18.6 miles) above earth's surface.
Most of our weather, however, occurs within the first 10 to 15 km. (6.2
to 9.3 miles)
Composition of Atmosphere
•
•
•
•
•
•
•
Nitrogen(N2) - 78%
Oxygen(O2) - 21%
Water Vapor (H2O) – 0 to 4%
Carbon Dioxide (CO2) - .037%
Methane (CH4)
Nitrous Oxide (N2O4)
Ozone (O3)
Atmospheric Gases
Nitrogen, oxygen, argon,
water vapor, carbon
dioxide, and most other
gases are invisible.
Clouds are not gas, but
condensed vapor in the
form of liquid droplets.
Ground based smog, which
is visible, contains reactants
of nitrogen and ozone.
Ozone – is the primary ingredient of smog!
Variable & Increasing Gases
Nitrogen and oxygen concentrations experience little change, but
carbon dioxide, methane, nitrous oxides, and chlorofluorocarbons
are greenhouse gases experiencing discernable increases in
concentration. CO2 has risen more than 18% since 1958. Fossil
fuels are the biggest problem!
Pressure & Density
Gravity pulls gases toward
earth's surface, and the
whole column of gases
weighs 14.7 psi at sea level,
a pressure of 1013.25 mb or
29.92 in.Hg.
The amount of
force exerted
over an area of
surface is called
air pressure!
Air Density is
The number of air
Molecules in a given
Space (volume)
Vertical Pressure Profile
Atmospheric pressure
decreases rapidly with
height. Climbing to an
altitude of only 5.5 km
(3.4 miles) where the
pressure is 500 mb,
would put you above
one-half of the
atmosphere’s
molecules.
Atmospheric Layers
8 layers are defined by constant
trends in average air
temperature (which changes
with pressure and radiation),
where the outer exosphere is
not shown.
1.
2.
3.
4.
5.
6.
7.
8.
Troposphere
Tropopause
Stratosphere
Stratopause
Mesosphere
Mesopause
Thermosphere
Exosphere
Atmospheric Layers
Tropopause separates
Troposphere from
Stratosphere. Generally
higher in summer
Lower in winter.
Troposphere – Temp decrease
w/ height. Most of our weather
occurs in this layer. Varies in
height around the globe, but
Averages about 11 km (6.8 M) in
height.
The troposphere is the lowest major atmospheric layer, and is located
from the Earth's surface up to the bottom of the stratosphere. It has
decreasing temperature with height (at an average rate of 3.5° F per
thousand feet (6.5 ° C per kilometer); whereas the stratosphere has
either constant or slowly increasing temperature with height. The
troposphere is where all of Earth's weather occurs. The boundary that
divides the troposphere from the stratosphere is called the
"tropopause", located at an altitude of around 5 miles in the winter, to
around 8 miles high in the summer, and as high as 11 or 12 miles in the
deep tropics. When you see the top of a thunderstorm flatten out into
an anvil cloud, like in the illustration above, it is usually because the
updrafts in the storm are "bumping up against" the bottom of the
stratosphere
The Stratosphere and Ozone Layer
Above the troposphere is the stratosphere, where air flow is mostly horizontal. The thin ozone layer in
the upper stratosphere has a high concentration of ozone, a particularly reactive form of oxygen. This
layer is primarily responsible for absorbing the ultraviolet radiation from the Sun. The formation of this
layer is a delicate matter, since only when oxygen is produced in the atmosphere can an ozone layer
form and prevent an intense flux of ultraviolet radiation from reaching the surface, where it is quite
hazardous to the evolution of life. There is considerable recent concern that manmade flourocarbon
compounds may be depleting the ozone layer, with dire future consequences for life on the Earth.
The Mesosphere and Ionosphere
Above the stratosphere is the mesosphere and above that is the ionosphere (or thermosphere), where
many atoms are ionized (have gained or lost electrons so they have a net electrical charge). The
ionosphere is very thin, but it is where aurora take place, and is also responsible for absorbing the most
energetic photons from the Sun, and for reflecting radio waves, thereby making long-distance radio
communication possible.
Atmospheric Layers
Stratosphere
Temperature inversion in
stratosphere. Ozone plays
a major part in heating the air
at this altitude
Atmospheric Layers
Mesosphere
Middle atmosphere – Air thin,
pressure low,
Need oxygen to live in this
region. Air quite Cold -90°C (130°F) near the top of
mesosphere
Atmospheric Layers
Thermosphere
“Hot layer” – oxygen
molecules absorb energy
from solar rays warming the
air. Very few atoms and
molecules in this Region.
Climate
Thanks to:P. Lobosco
What Causes Climate?
 Climate is the name for the general
conditions of temperature and precipitation
for an area over a long period of time. The
climate of a region is determined by two
basic factors: temperature and
precipitation.
Factors that Affect Temperature
Latitude
Elevation
The presence of ocean
currents
Latitude
 Latitude is the measure of the distance
north and south of the equator. Latitude is
measured in degrees. Areas close to the
equator, 0 degrees latitude, receive the
direct rays of the sun. These direct rays
provide the most radiant energy.
Elevation
 Elevation, or altitude, is the distance above
sea level. As elevation increases, the air
becomes less dense. This means there are
fewer gas molecules in the air and they are
spread far apart. Less- dense air cannot
hold as much heat as denser air. So as
elevation increases, temperature decreases.
Location
 The surface temperature of water affects the
temperature of the water above it. Warm water
warms the air and cold water tends to cool it.
Land areas near warm water currents have warm
temperatures. The Gulf Stream is an ocean current
that carries warm water along the eastern coast of
the United States. The California Current travels
toward the equator carrying cold water along the
west coast of the United States.
Factors that Affect Precipitation
The two factors that affect the
amount of precipitation at a
particular location are:
 prevailing winds
 mountain ranges.
Prevailing Winds
A wind that blows more often
from one direction than from
any other direction is called a
prevailing wind. Prevailing
winds have a great influence on
the climate of regions in their
path
Direction of Prevailing Winds
 The direction from which a prevailing wind
blows also affects the amount of moisture it
carries. Some prevailing winds blow from
the water to the land (sea breeze).
Mountain Ranges
 The amount of precipitation at a particular
location is also affected by mountain ranges. A
mountain range acts as a barrier to prevailing
winds. The windward side of a mountain has a
wet climate. On the leeward side, relatively dry
air moves down the side of the mountain and
results in very little precipitation. A good example
is the Great Basin on the leeward side of the Sierra
Nevada Mountain Range.
Climate Zones
 The Earth’s climate can
be divided into general
climate zones according
to average temperatures.
Scientist classify localized
climates as
microclimates. The three
major climate zones on
the Earth are the polar,
temperate, and tropical
zones.
Polar Zones
 In each hemisphere, the polar zone extends from
the pole to about 60 degrees latitude. In polar
zones, the average yearly temperature is below
freezing. There are some areas in the polar zones,
such as the northern coasts of Canada and Alaska
and the southern tip of South America, where the
snow melts during the warmest part of the year.
Temperate Zones
 In each hemisphere, the temperate zone is found
between 60 degrees and 30 degrees latitude. In
the areas of the temperate zones farther from the
equator, snow is common in the winter. In the
areas of the temperate zones closer to the
equator, rain normally falls all year round. The
average amount of precipitation is about the
same throughout. The average temperatures
range from 5 degrees C to 20 degrees C (41 to 68
F).
Tropical Zones
 The tropical zones, which extend from 30 degrees
north and south latitude to the equator, have high
temperatures and high humidity. Tropical zones
are also known as low-latitude climates. The
average temperature during the coldest month of
the year does not fall below 18 degrees C (65 F).
Many deserts are located on the western coasts of
the continents. This is because the prevailing
winds, the trades, blow from east to west.
Marine and Continental Climates
 Within each of the three major climate zones,
there are marine and continental climates. Areas
near an ocean or other large body of water have a
marine climate. Areas located within a large
landmass have a continental climate. Areas with a
marine climate receive more precipitation and
have a more moderate climate. A continental
climate has less precipitation and a greater range
in climate.
Changes in Climate
 The three natural factors responsible for climate
changes are
 the slow drifting of the continents,
 changes in the sun’s energy output
 and variations in the position of the Earth relative to
the sun.
 These natural factors are not related to human
activity. The results of the human activity of the
burning of fossil fuels may also lead to changes in
climate.
Short Term Changes in Climate
 Some short-term changes may be the result of changes in
ocean currents and global winds. Ocean currents help
transfer heat to the atmosphere. This process generates
global winds. The global winds help move ocean currents.
Any major change in an ocean current can cause a change
in climate. El Nino and La Nina are examples.
La Nina & El Nino
 La Niña is characterized by unusually
cold ocean temperatures in the
Equatorial Pacific, compared to El
Nino, which is characterized by
unusually warm ocean temperatures in
the Equatorial Pacific.