Weather Patterns 16.1 The atmosphere's air pressure changes. 16.2 CHAPTER NEW CHAPTER Weather Patterns the BIG idea Some features of weather have predictable patterns. 16.1 The atmosphere's air pressure changes. 16.2 The atmosphere has wind patterns. 16.3 Most clouds form as air rises and cools. 16.4 Water falls to Earth’s surface as precipitation. CHAPTER OUTLINE CHAPTER RESOURCES

The atmosphere's air pressure changes. 16.1 The atmosphere's air pressure changes. Air pressure is the force of air molecules pushing on an area. Air pressure decreases as you move higher in the atmosphere. Air pressure can also differ in two locations at the same altitude. air pressure barometer CHAPTER RESOURCES SECTION OUTLINE

16.1 air pressure The atmosphere's air pressure changes. barometer The force of air molecules pushing on an area. CHAPTER RESOURCES KEY CONCEPT SUMMARY

16.1 barometer The atmosphere's air pressure changes. An instrument that measures air pressure in the atmosphere. CHAPTER RESOURCES KEY CONCEPT SUMMARY

The atmosphere has wind patterns. 16.2 The atmosphere has wind patterns. Wind blows from areas of high pressure toward areas of low pressure. Earth's rotation causes long distance winds to curve. weather wind global wind Coriolis effect jet stream area of high pressure area of low pressure monsoon VISUALIZATION View an animation of the Coriolis effect. CLASSZONE.COM Explore how breezes blowing over land and water change over the course of a day. CHAPTER RESOURCES SECTION OUTLINE

16.2 weather The atmosphere has wind patterns. global wind The condition of Earth’s atmosphere at a particular time and place. Coriolis effect jet stream monsoon CHAPTER RESOURCES KEY CONCEPT SUMMARY

16.2 wind The atmosphere has wind patterns. weather wind wind global wind The horizontal movement of air caused by differences in air pressure. Coriolis effect jet stream monsoon CHAPTER RESOURCES KEY CONCEPT SUMMARY

16.2 global wind The atmosphere has wind patterns. weather global wind wind global wind Winds that travel long distances in steady patterns over several weeks. Coriolis effect jet stream monsoon CHAPTER RESOURCES KEY CONCEPT SUMMARY

16.2 Coriolis effect The atmosphere has wind patterns. weather Coriolis effect wind global wind The influence of Earth’s rotation on objects that move over Earth. Coriolis effect jet stream monsoon CHAPTER RESOURCES KEY CONCEPT SUMMARY

16.2 jet stream The atmosphere has wind patterns. weather jet stream wind global wind A wind that flows in the upper troposphere from west to east over vast distances at great speeds. Coriolis effect jet stream monsoon CHAPTER RESOURCES KEY CONCEPT SUMMARY

16.2 monsoon The atmosphere has wind patterns. weather monsoon wind global wind A wind that changes direction with the seasons. Coriolis effect jet stream monsoon CHAPTER RESOURCES KEY CONCEPT SUMMARY

Most clouds form as air rises and cools. 16.3 Most clouds form as air rises and cools. Clouds are made of tiny water droplets that condense from water vapor in rising air. evaporation condensation level where condensation begins precipitation humidity saturation relative humidity dew point CHAPTER RESOURCES SECTION OUTLINE

16.3 evaporation Most clouds form as air rises and cools. condensation precipitation The process by which a gas changes into a liquid. humidity saturation relative humidity dew point CHAPTER RESOURCES KEY CONCEPT SUMMARY

16.3 condensation Most clouds form as air rises and cools. evaporation condensation condensation precipitation The process by which a gas changes into a liquid. humidity saturation relative humidity dew point CHAPTER RESOURCES KEY CONCEPT SUMMARY

16.3 precipitation Most clouds form as air rises and cools. evaporation precipitation condensation precipitation Any type of liquid or solid water that falls to Earth’s surface, such as rain, snow, or hail. humidity saturation relative humidity dew point CHAPTER RESOURCES KEY CONCEPT SUMMARY

16.3 humidity Most clouds form as air rises and cools. evaporation humidity condensation precipitation The amount of water vapor in air. humidity saturation relative humidity dew point CHAPTER RESOURCES KEY CONCEPT SUMMARY

16.3 saturation Most clouds form as air rises and cools. evaporation saturation condensation precipitation A condition of the atmosphere in which the rates of evaporation and condensation are equal. humidity saturation relative humidity dew point CHAPTER RESOURCES KEY CONCEPT SUMMARY

16.3 relative humidity Most clouds form as air rises and cools. evaporation relative humidity condensation precipitation The comparison of the amount of water vapor in air with the maximum amount of water vapor that can be present in air at that temperature. humidity saturation relative humidity dew point CHAPTER RESOURCES KEY CONCEPT SUMMARY

16.3 dew point Most clouds form as air rises and cools. evaporation dew point condensation precipitation The temperature at which air reaches saturation. humidity saturation relative humidity dew point CHAPTER RESOURCES KEY CONCEPT SUMMARY

Water falls to Earth’s surface as precipitation. 16.4 Water falls to Earth’s surface as precipitation. Water droplets in clouds merge to form raindrops. freezing rain sleet hail Ice crystals in clouds can form snow, rain, and other types of precipitation. acid rain Freezing rain is rain that freezes when it hits the ground or other surfaces. Sleet is rain that freezes into ice pellets while falling through cold air. Snow forms from ice crystals that merge in clouds. Hail forms when ice pellets move up and down in clouds, growing larger as they gain layers of ice. CHAPTER RESOURCES SECTION OUTLINE

16.4 freezing rain Water falls to Earth’s surface as precipitation. sleet hail Rain that freezes when it hits the ground or another surface and coats the surface with ice. acid rain CHAPTER RESOURCES KEY CONCEPT SUMMARY

16.4 sleet Water falls to Earth’s surface as precipitation. freezing rain sleet sleet hail Small pellets of ice that form when rain passes through a layer of cold air and freezes before hitting the ground. acid rain CHAPTER RESOURCES KEY CONCEPT SUMMARY

16.4 hail Water falls to Earth’s surface as precipitation. freezing rain hail sleet hail Layered lumps or balls of ice that fall from cumulo-nimbus clouds. acid rain CHAPTER RESOURCES KEY CONCEPT SUMMARY

16.4 acid rain Water falls to Earth’s surface as precipitation. freezing rain acid rain sleet hail Rain that has become more acidic than normal due to pollution. acid rain CHAPTER RESOURCES KEY CONCEPT SUMMARY

16.1 The atmosphere's air pressure changes. I. The atmosphere's air pressure changes. air pressure A. Air exerts pressure. barometer B. Air pressure is related to altitude and density. 1. Pressure and Air Motion 2. Barometers and Air Pressure CHAPTER RESOURCES KEY CONCEPT SUMMARY

The atmosphere has wind patterns. 16.2 The atmosphere has wind patterns. II. The atmosphere has wind patterns. weather A. Uneven heating causes air to move. wind B. Earth’s rotation affects wind direction. global wind C. Bands of calm air separate global wind belts. Coriolis effect 1. Calm Regions jet stream 2. Wind Belts monsoon 3. Effects of Wind on Travel D. Jet streams flow near the top of the troposphere. E. Patterns of heating and cooling cause local winds and monsoons. CHAPTER RESOURCES 1. Local Winds 2. Monsoons KEY CONCEPT SUMMARY

Most clouds form as air rises and cools. 16.3 Most clouds form as air rises and cools. III. Most clouds form as air rises and cools. evaporation A. Temperature affects water in the air. condensation 1. Water in the Air precipitation 2. Humidity and Relative Humidity humidity B. Water vapor condenses and forms clouds. saturation 1. Characteristics of Clouds relative humidity 2. Cirrus Clouds dew point 3. Cumulus Clouds 4. Stratus Clouds CHAPTER RESOURCES 5. Fog KEY CONCEPT SUMMARY

Water falls to Earth’s surface as precipitation. 16.4 Water falls to Earth’s surface as precipitation. IV. Water falls to Earth’s surface as precipitation. freezing rain A. Precipitation forms from water droplets or ice crystals. sleet hail 1. Measuring Precipitation acid rain 2. Types of Precipitation B. Precipitation can carry pollution. CHAPTER RESOURCES KEY CONCEPT SUMMARY

Image Gallery Click on the icons to see a larger image or animation. CHAPTER HOME Image Gallery Click on the icons to see a larger image or animation. VISUALIZATION View an animation of the Coriolis effect. CLASSZONE.COM Explore how breezes blowing over land and water change over the course of a day.

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