Download Changes to Earth`s Surface Chapter 9

Weather and the Water
Cycle Chapter 11
Lesson 1: What Causes Weather?
Lesson 2: What Conditions Affect the Water Cycle ?
Lesson 3: How Can patterns in Weather Be Observed?
Lesson 1: VOCABULARY
 Atmosphere: the blanket of air surrounding
Earth.
 Troposphere: the layer of air closest to
Earth’s surface.
 Air Pressure: weight of the atmosphere
pressing down on Earth.
 Local Winds: movements of air that result
from local changes in temperature.
 Prevailing wind: Global winds that blow
constantly from the same direction
Lesson 1: The Atmosphere
 If Earth were the size of a
peach, the atmosphere
would be thinner than the
peach’s fuzz.
 The troposphere contains
about 90% of the gases in
the atmosphere.
 The stratosphere contains
most of the Earth’s ozone.
 Ozone is a gas that
protects Earth from the
sun’s ultraviolet rays
 Cold air is more dense
than warm air, so it is
heavier than warm air
Lesson 1: Uneven Heating
 The air around you is always
moving and changing
 When the sun’s energy
reaches Earth, some of the
energy bounces off objects.
Different types of surfaces
absorb or reflect this energy

Example- Sand on a
beach is much hotter
than the water near the
sand
 Because of this, the air over
the beach will be hotter, too.
The air over the water-cooler
Lesson 1: Local Winds/Prevailing Winds
 Wind results from air
moving from areas of high
air pressure to areas of
low pressure
 Local winds often
occur on lakeshores or
seashores
 Wind that always blow in
the same direction is a
prevailing wind
 Uneven heating of
large areas of Earth’s
surface cause these
Lesson 2: Vocabulary
 Water Cycle- process in which water continuously
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moves from Earth’s surface into the atmosphere and
back again
Evaporation- process of a liquid changing into a gas
Condensation- process of a gas changing into a
liquid
Humidity- measurement of the amount of water
vapor in the air
Precipitation- Water that falls from the air to Earth
Lesson 2: What Conditions Affect the
Water Cycle?
 The Water Cycle is important because:
 People plants, and animals need fresh water to live.
 Without rain and snow, we wouldn’t have drinking water.
 We also would not have water to grow crops for feeding.
 It constantly recycles water in lakes, rivers, streams, and
oceans.
 It keeps groundwater flowing, which is water underground.
Lesson 2: Clouds and Precipitation?
 A large part of the water cycle
occurs in the atmosphere
 The more water vapor in the air,
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
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the more humid the air is.
Warm air usually have more water
vapor in it that cold air does
As more and more water
condenses, a cloud forms
A cloud is basically dust and
condensed water.
When water droplets inside a cloud
are too heavy to stay up they fall to
the Earth as.
 Rain
 Snow
 Sleet
 Hail
Lesson 2: Factors that Affect the Water
Cycle?
 Factors:
 How close a
place is to Earth’s
poles or the
equator.
 The shape of the
land
 Landforms and
Temperature
Lesson 3: Vocabulary
 Air Mass- A large body of air that has similar
temperature and humidity throughout.
 Front- The border where two air masses
meet.
 Climate- The Pattern of weather an area
experiences over long period of time.
Lesson 3: How Can Patterns in
Weather Be Observed?
 Measuring Weather:
 Because there are many different kinds of weather data,
you need many different instruments
 A thermometer measures air temperature.
 A hygrometer measures humidity (amount of water in air)
 A barometer measures air pressure
 An anemometer measures wind speed
 A Doppler Radar gives a view of the weather from above
Lesson 3: Air Masses and Fronts
 Air masses can be
warm or cold, humid or
dry: they take on
characteristics of the
region over which it
forms
 When the weather
changes in an area, it
means that the air mass
over the area is
changing too.
Lesson 3: Fronts
 The border where two
air masses meet is
called a front
 Most weather changes
occur along a front
 There are two main
kinds of fronts cold
and warm: When
warm fronts get
pushed up by cold
fronts, heavy rain and
thunderstorms occur
Lesson 3: Weather Patterns and
Climates
 Weather in most
locations occur in
regular patterns:
 In addition to wind patterns,
there are temperature
patterns
 Over a long time, there are
seasonal patterns
 Like daily patterns, seasonal
weather patterns are driven by
the sun
Lesson 3: Landforms Affect Climate
Mountains affect the water cycle by forcing air to rise
and cool
-This causes rain or snow on the side of the mountain
to faces the wind
-As air sinks, its humidity goes down even more.
Oceans can also affect an area’s climate
-land near a large body of water tends to have a milder
climate than other areas.
-This land is usually cooler in summer, warmer in
winter, and more humid all year than areas farther
inland