1. 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?

2. 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

3. 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

4. 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

5. 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

6. Lesson 2: Vocabulary
Water Cycle- process in which water continuously 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

7. 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.

8. Lesson 2: Clouds and Precipitation?
A large part of the water cycle occurs in the atmosphere
The more water vapor in the air, 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

9. Lesson 2: Factors that Affect the Water Cycle?
How close a place is to Earth’s poles or the equator.
The shape of the land
Landforms and Temperature

10. 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.

11. 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

12. 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.

13. 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

14. 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

15. 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