Transcript The Role of Solar Energy (continued)

The Role of Solar Energy
(continued)
Page 181
Water has a high specific heat- heats up and
cools down much slower than land
This causes unequal heating of the Earth’s surface
Unequal Heating of the Earth
• As the sun’s energy
strikes the Earth, the
Earth’s surface is heated
unequally.
Unequal Heating of the Earth
• This occurs because
land heats up and cools
down faster than water.
Unequal Heating of the Earth
• If you have ever been to a pool in the
summer, you have experienced this
unequal heating. In the middle of the
afternoon the concrete surrounding a pool
feels very hot while the pool water feels
cool. In the evening, however, the
concrete will feel cool to your bare feet
and the pool water will feel warm.
Unequal heating powers
atmosphere and oceans.
• This unequal heating and
cooling powers the
motion of the
atmosphere and the
oceans.
Warm Air/Warm Water Rise
• When air and water are
heated, their molecules move
faster and farther apart. This
reduces the density of the
water and air causing their
molecules to rise.
Cool Air/Cool Water Fall
• On the other hand,
cooler air and water
molecules move slower,
are denser, and begin to
descend or fall.
Convection
• In the atmosphere rising
warm air and descending
cooler air forms a cyclic, or
circular, rising and falling
pattern called convection.
Unequal Heating Causes Air To
Move
Moving Air Is Called WIND
Convection in Air
Convection in Water
• This same circular motion caused by
heated molecules occurs in water as
warmer, less dense water rises and cooler,
denser water falls.
Convection Moves Ocean Water
Click for movie clip
• Radiation and convection from the Earth’s
surface transfer or distribute heat energy.
This energy powers the global circulation
of the atmosphere and the oceans.
Evaporation Leads to Clouds
• As oceans, lakes, and rivers
absorb heat energy, water
vapor is carried up into the
atmosphere by rising warm
air.
Evaporation Leads to Clouds
• Water vapor is formed
from water that
evaporates from the
Earth’s surface.
Evaporation Leads to Clouds
• As the warm air rises, it
actually gives off some heat as
the water vapor in it cools
down and changes into
minute, or tiny, condensed
water particles.
Evaporation Leads to Clouds
• As more and more of these
condensed water particles join
together, a cloud is formed. If
the water particles become too
large and heavy, they fall to
the ground as precipitation.
Rapidly Moving Hot Air Can
Cause…
• When heated air rises rapidly into the
atmosphere, the result can be a storm.
• A storm is a violent weather condition
caused by a disturbance in the Earth’s
atmosphere.
Rapidly Moving Hot Air Can
Cause…
• One kind of storm is a thunderstorm.
Thunderstorms usually have strong winds,
heavy rain, thunder, and lightning. Some
thunderstorms are formed when the land
is strongly heated. This results in a mass
of cooler air forcing its way underneath
rising warm air.
Rapidly Moving Hot Air Can
Cause…
• Hurricanes are another type of storm that
forms due to the rising and falling
convection patterns.
• Hurricanes form over warm, tropical water.
They begin as thunderstorms and grow
larger as they take in more and more heat
and moisture from the warm ocean water.
The Formation of a Hurricane
Hurricanes 101