Download atmosphere_and_wind - Red Hook Central Schools

The Atmosphere
A thin fragile shell of gases
that provides all our weather
and allows life on earth
thermosphere
troposphere
stratosphere
mesosphere
Air is
mostly nitrogen (78%)
and oxygen (21%)
In humid air, water vapor
becomes a significant
gas
Atmosphere Basics
 The lower atmosphere is a fairly
homogeneous mixture of gases.
 Water vapor occupies up to 4%
of the volume of the atmosphere
 The density of air is influenced
by temperature and water content
The red line
is air pressure
What happens
to pressure with
increasing
altitude?
Why is this so?
Atmospheric Pressure
• Pressure is measured by barometers
• Warm air is less dense, therefore has
lower pressure
• Cold air is more dense, therefore has
higher pressure
• Humid air (lots of water vapor) has lower
pressure, since H20 (18) weighs less than
N2 (28)
Air pressure can be
measured with a
simple mercury
barometer
This type of barometer
measures pressure in
inches or centimeters
of mercury
Remember though
that air pressure
is exerted in all
directions and
not just down
Or with a spring
type barometer
called an
Aneroid
barometer
This type of
barometer uses
units of pressure
called millibars
or it can also
show inches of
mercury
Average sea level pressure = 29.92” of mercury = 1013.2 millibars
This is also known as 1 atmosphere
How the Atmosphere is Heated
The SUN is the source of most heat
In general, the more INSOLATION , the
warmer the atmosphere (and the Earth’s
surface) will be
How the Atmosphere is Heated
1) Conduction: hot Earth warms air above
it
2) Direct absorption of Sun’s heat by gases
in atmosphere
3) Absorption of infrared heat radiated from
Earth’s surface
4) Condensation of water releases stored
heat
5) Coriolis affect: friction between
atmosphere and Earth due to rotation
From Reference Tables
What is the reason for
the temperature soaring
In the thermosphere?
What is the reason for
the temperature rise
In the stratosphere?
What is the reason
for the temperature
drop in the troposphere?
How Heat is Transferred in the
Atmosphere
1) Convection currents: density differences
moves air in circles (wind)
2) Rising air (less dense) cools as it
expands
RECC (Rising air Expands Cools Condenses)
3) Sinking air (more dense) heats up as it is
compressed
SCWE (Sinking air Compresses Warms Evaporates)
Why will these balloons
Rise into the atmosphere?
Yes because the air in th
Becomes hotter and less
dense than the surround
air
As long as the air in the
balloons stays warmer
than the surrounding air
it will continue to rise up
Usually the temperature
gets colder with increasing
height in the troposphere
Moving Air is called WIND.
What causes WIND?
 Uneven solar heating
 The Coriolis effect
Uneven Solar Heating and
Latitude
Uneven Solar Heating and
Latitude
Moving masses
of air and
ocean currents
transport
energy from
locations with a
surplus to
those with a
deficit.
The Coriolis Effect
deflection of a moving object, caused by the
moving frame of reference on the spinning Earth.
How does this apply to the atmosphere?
As air warms, expands, and rises at the equator,
it moves toward the pole, but instead of traveling
in a straight path, the air is deflected eastward.
In the N. Hemisphere air turns to the right.
In the S. Hemisphere air turns to the left.
Heat Transport + Coriolis
Wind Patterns
Cell Circulation Drives Wind Patterns
The doldrums are calm equatorial areas where
two Hadley cells converge.
The horse latitudes are areas between Hadley
and Ferrel cells. There is little surface wind in
this area.
The trade winds are surface winds of Hadley
cells.
The westerlies are surface winds of Ferrel cells.
2-D Winds
Differential Heating
Monsoons are seasonal patterns of wind
circulation. Characterized by dry winters and
wet summers.
Sea breeze is cool air from over the water
moving toward land. Sea breezes occur after
sunrise.
Land breezes occur after sunset when air
cooled by the land blows toward the water.
Sea Breezes And Land Breezes
Top: Sea breeze
Bottom: Land breeze
Monsoon:
A seasonal wind that
changes direction
from NE in winter to
SW in summer
RAINY SEASON!
Atmospheric Circulation
High altitude air current of very strong westerly winds
( up to 250 mph) flowing above the middle latitudes.
Effect of Air Movement on Water
• Friction between moving air and water
causes WAVES
• Ocean Currents are caused by the
prevailing winds, and tend to show circular
patterns due to Coriolis affect: spin
clockwise in N. Hemisphere,
counterclockwise in S. Hemisphere