Chapter 7 Weather Patterns Study Guide Pre-Vocabulary Atmosphere-The layers of gases that surround Earth. Ozone-A form of oxygen gas that makes a layer in the atmosphere that screens out much of the Sun’s ultraviolet rays. Vocabulary Lesson 1 The Atmosphere and Weather P. 364 insolation-The amount of the Sun’s energy that reaches Earth. P. 366 troposphere-The atmospheric layer of gases that is closest to Earth’s surface. Weather occurs in the troposphere. P. 366 weather-What the troposphere is like at any given place and time. P. 367 air pressure-The force put on a given area by the weight of the air above it. P. 369 humidity-The amount of water vapor in the air. P. 370 global wind-A wind that blows steadily in a predictable direction over long distances. P. 374 barometer-A device for measuring air pressure. P. 374 anemometer-A device for measuring wind speed. The Earth is shaped like a sphere. Sunlight strikes Earth most directly at the equator. It is colder closer to the poles because the sun’s rays strike at a less direct angle and the heat spreads out. When sunlight hits at a wider angle, the sunlight covers a larger area. The temperature of the land increases faster than the temperature of the water. As the land warms up, it heats the air above it. Air over the land becomes warmer than air over the sea. Temperature over land fluctuates more than temperature over water because the land heats up more rapidly during the day and cools down more rapidly at night. Vocabulary Lesson 2 Clouds and Precipitation P. 384 air mass-A large region of the atmosphere in which the air has similar properties. P. 384 front-The boundary between two air masses. P. 388 weather map-A map that shows the weather in a specific area at a specific point in time. *A cloud forms from water vapor particles slowing down and coming together. *The appearance of a cloud depends on how high it forms in the atmosphere and what the temperature there is. Precipitation is hail, rain, sleet and snow. Know the types of clouds from the picture handout Cirrus Clouds-Form at the highest altitudes/usually form from ice crystals when liquid water is cooled below its freezing point of 0 C (32 F). Cumulus Clouds-Form from water droplets/puffy clouds that form at middle altitudes Cumulonimbus-Large billowing, mushroom-like associated with T-storms, heavy rain and hail Stratus Clouds-Form from water droplets/are layered and form at low altitudes Three types of solid precipitation are sleet, hail, and snow. A rain gauge can give an accurate measure of rainfall in depth using a scale in millimeters or inches. The jet stream is another type of global wind. The jet stream is a high-altitude wind caused by large temperature differences between air masses. The jet stream winds can exceed speeds of 240 km per hour (150 miles per hour). Over North America, the jet stream blows from west to east. Because of the jet stream, we can predict the weather west of our location. There are three main types of fronts-cold, stationary, and warm fronts. Warm, humid air has low air pressure. The warm air will rise, cool, condense, and form clouds. Precipitation can follow. High-pressure systems bring clear, dry weather because the moisture evaporates before it can form clouds. Vocabulary Lesson 3 Severe Storms P. 394 thunderstorm-A rainstorm with both lightning and thunder. P. 398 tornado-A rotating funnel-shaped cloud with wind speeds up to 500 kilometers per hour or 300 miles per hour. P. 400 hurricane-A very large, swirling storm with very low pressure at the center, and wind speeds greater than 119km/h or 74 mph. P. 401 storm surge-A bulge of water in the ocean caused by hurricane waves and winds. P. 401 cyclone-Any storm with a low-pressure center that causes a circular pattern of winds to form. Tropical storms, hurricanes, and tornados are all cyclones. Why do you often hear thunder when you see lightning? Lightning heats the air around it so much that the air expands violently. This violent expansion of air makes the sound called thunder. Cause and Effect: What happens as a thunderstorm forms? A cold front moves in and pushes warm, humid air upward. As the air rises, it cools and water vapor condenses. Released energy from condensation warms the air and causes updrafts. The water droplets combine and grow larger until they fall. How are hurricanes and tornados alike? In both, air rotates around a center. Hurricanes fastest winds and heaviest rains are found around the eye. A tropical storm turns into a hurricane when the wind speed in the storm reaches more than 119 kilometers (74 miles) per hour. What does a meteorologist use to create weather maps and make predictions? Meteorologists use data collected about temperature, wind speed, wind direction, and air pressure to create weather maps. A meteorologist may use information from radar to predict when a storm will arrive and how intense it will be. Weather satellites take pictures of the atmosphere from space. Vocabulary Lesson 4 Climate P. 408 climate-The average weather pattern of a region. Latitude is the most important factor in determining climate. The equator is in the tropical climate zone. The climate is warm and wet. The U.S. is in the temperate climate zone. Summers are warm, and winters are cool or cold. Precipitation falls all year round. P. 410 current-An ocean movement; a large stream of water that flows in the ocean. The Gulf Stream is a surface current runs along the East Coast of the United States and across the Atlantic Ocean. It carries warm water from near the equator toward the poles. It is one of the strongest known currents. The Spanish explorer Juan Ponce de León was the first to describe the Gulf Stream in 1513 as he searched for the fountain of youth in what is now Florida. It has a warming effect on climates in the Southeastern part of the United States, Florida and Europe. Other currents carry cold water from the poles toward the equator. P. 411 rain shadow-The dry area on the leeward side of a mountain. P. 412 El Nino-A change in weather conditions caused by the sinking of the cold current in the Pacific Ocean. Higher tides, heavy rains, and storms occur along the coasts of North and South America. How Does Climate Affect the Way People Live? Climate has a big impact on our lives. It influences the crops we can grow and when to plant, how we dress, and perhaps even how we feel. Climate influences almost all aspects of life from the jobs people do to the sports and leisure activities people take part in. What jobs and sports are affected by wind speed and direction. Why do they rely on the wind? Be prepared to explain your answer.