Winds
Energy From the Sun
The atmosphere is the mixture of gases
that surrounds the Earth. It is divided
into 4 layers classified by temperature.
Energy in the Atmosphere
• energy in Earth’s atmosphere comes
from the sun
• energy travels as electromagnetic
waves
• Most of the energy is in the form of
visible light and infrared radiation
• A small amount of ultraviolet
radiation
Electromagnetic Energy
• Different forms of electromagnetic
energy have different wavelengths.
• Examples of electromagnetic energy
are:
–
–
–
–
–
–
microwaves
infrared light
visible light
ultraviolet light
X-rays
gamma rays.
Visible light
• Mixture of colors (ROYGBIV)
• Different colors result of different
wavelengths
Infrared Radiation
• Wavelengths LONGER than red light
• Not visible
• Felt as heat
Ultraviolet radiation
• Wavelengths that are
SHORTER than violet
light
• Not visible
• Causes sunburns, eye
damage, skin cancer
• Ozone in the
stratosphere blocks
most of the UV
radiation
Heating of the atmosphere
• Some of the energy is
reflected/absorbed in the atmosphere
• The rest is reflected/absorbed by the
surface.
• The greenhouse effect is a natural
process by which gases hold heat in the
air warming our planet.
Heat Energy
• Thermal energy is the total energy of motion in
the molecules of a substance.
• “Heat" is used when energy is transferred
from one substance to another.
Heat Energy Moves
Heat moves
from warmer
objects to cooler
ones until they
reach the same
temperature.
Heat Energy Moves
• Heat can be transferred through:
– Transfer of heat by direct contact
(conduction)
– Transfer by electromagnetic waves
(radiation.)
– In a liquid or gas, currents will cause
the transfer of heat (convection.)
Heat Moves Through the
Atmosphere
• Convection causes most of the heating
of the troposphere.
• The upward movement of warm air and
the downward movement of cool air
form convection currents.
• These currents cause wind.
What is wind?
• Warm air expands and
rises creating low
pressure.
• Cold air sinks and
creates high pressure.
• Winds are caused by
differences in air
pressure.
• Winds move from high
to low pressure.
Summary
• Heating of Earth’s
surface and
atmosphere by
the Sun drives
convection within
the atmosphere
producing winds.
Local winds
• winds that blow over
short distances
• Sea and land
breezes
• Unequal heating
results in
differences in
pressures causing
winds to blow
Sea/lake and land breezes
Global winds
•Winds that
blow steadily
from specific
directions over
long distances
•Temperature
differences
between the
equator and the
poles creates
giant convection
currents
Coriolis Effect
• Global winds do
NOT blow in a
straight line
• The Earth’s
rotation causes
the global winds
to curve
Major Global Wind Belts
• Trade winds
• Prevailing
westerlies
• Polar
easterlies
Horse Latitudes and Doldrums
• Areas
of
little
to no
wind
Animation of global wind belts
• http://vortex.weather.brockport.edu/~swe
inbec/class/04_GlobalWind.swf