Download Chapter 11 Lesson 1 Notes

Chapter 11
Lesson 1: What Causes Weather?
Objectives:
 Identify the causes of weather
 Describe the atmosphere
 Recognize how winds from
Vocabulary
 atmosphere
 troposphere
 air pressure
 local winds
 prevailing winds
The Atmosphere
The earth is surrounded by a blanket of air called the __________________. In
comparison to the earth, the __________________ is much thinner. If a peach were
the size of the earth than the atmosphere would be thinner than the fuzz on the peach!
The atmosphere is made up of several __________________ and each layer has a
different temperature ranging from cold to warm to hot. The layer closest to the earth
is called the __________________. This layer is about __________________ thick.
The earth’s highest mountains are within the troposphere. The atmosphere is made up of
different gases and the troposphere contains about __________ of the gases in the
atmosphere. The troposphere also contains water, ____________, and other tiny
__________________. Most of the weather we witness on earth occurs in this layer of
the atmosphere.
After the troposphere the next layer of the atmosphere is the
__________________. Most of the earth’s ______________ is in the stratosphere.
__________________ is a gas that protects the earth’s surface from harmful things
such as ultraviolet rays from the sun. Clouds are very rare in this layer because the air in
this layer of the atmosphere is very dry. Above the stratosphere there is less air and the
outermost layer of the atmosphere extends into space.
The atmosphere has many gas molecules which are constantly moving.
__________________ pulls them to the earth’s surface and as a result the air near the
earth’s surface is dense and has weight. The weight of the atmosphere pressing down on
the earth is called ______ __________________.
There is more air closer to the earth’s surface than away from it. This is why
______ __________________ is greater (more air pressure) at sea level than it is on
a mountain. This is because a mountain is not at sea level. __________________ also
affects air pressure. Cold air is more dense than warm air, so it is heavier than warm air.
Because cold air is more dense, it exerts more pressure on the earth.
Uneven Heating
The air around you is constantly __________________ or changing. You know this
because the air felt one way when you left home this morning and if you were to step out
now it would not feel the same outside as it did in the morning.
When the sun’s energy reaches the earth, some of the energy
__________________ off objects such as clouds and earth __________________
the rest of the energy. Earth has many different surfaces and many of these surfaces
absorb different amounts of energy.
Chart/Diagram work
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50% of the sun’s energy is absorbed by the __________________ surface.
5% of the sun’s energy is __________________ by the __________________
surface.
Some energy from the sun is __________________ or __________________ in
the atmosphere.
25% of the sun’s energy is absorbed and __________________ by clouds.
20% of the sun’s energy is reflected and __________________ by air.
Remember, cold air is denser than warm air. Dense air is heavy therefore cold air is
heavier than warm air. Because of this cold air ______________ and air that is less
dense (less heavier) is pushed up. Cold air sinks and warm air is pushed up; this sinking and
rising of air causes _____________. The atmosphere has cold air and warm air and the
uneven heating of the atmosphere is wind (the movement of air).
Local Winds
Wind results from air moving from areas of _____________ air pressure to areas
with __________ air pressure. Cool air has a higher pressure than warm air and because
of this wind blows from __________________ places toward __________________
places.
Sometimes two places in the same area have different temperatures. This
produces a __________ ___________. This is a wind that results from a
__________________ difference in temperature. Local winds occur on
__________________ or __________________. During the day, the ____________
over land is __________________ than the air over the water. The air that is over the
water is more dense and as a result a wind is formed that blows from the ____________
to the land. This type of wind is known as a ________ _______________.
To sum it up, during the day the wind blows from over the water to over land
because during the day the air is heavier (more dense) over the water so the land is
warmer.
In the evening, the wind blows the opposite way. Once the land becomes more
cooler than the water, a wind blows from the _______________ to the
_____________. This is called a _____________ _____________.
Interpreting Visuals
Directions: Look at the diagram on page 401 and answer the following questions:
1) What is a sea breeze? At what time of the day does it occur?
2) What is a land breeze? At what time of the day does it occur?
Prevailing Winds
There are other more constant winds which are called __________________
_________. These winds are global and always blow in the ______________ direction.
The uneven heating of large areas of earth’s surface causes ____________ _________.
The __________________ of the earth also affects prevailing winds.
There are 2 poles on the earth and are covered by ice. Depending on the time of
the year, the poles receive indirect __________________ or no sunlight at all, so they
are always __________. The equater of the earth constantly gets ____________ all
year round, so it is always warm. The cold air that is above the air sinks and moves toward
the equator and at the same time the air at the equator moves up and goes toward the
poles. Air moves in curved paths due to the earth’s rotation. This __________________
causes prevailing winds to blow mainly from either the _____________ or the west.