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Standardized Test Prep
Resources Chapter Presentation Visual Concepts Transparencies Standardized Test Prep Brain Food Video Quiz

Chapter 24 Table of Contents Section 1 Air Masses Section 2 Fronts
Weather Table of Contents Section 1 Air Masses Section 2 Fronts Section 3 Weather Instruments Section 4 Forecasting the Weather

Chapter 24 Objectives Explain how an air mass forms.
Section 1 Air Masses Objectives Explain how an air mass forms. List the four main types of air masses. Describe how air masses affect the weather of North America.

Chapter 24 Section 1 Air Masses Air Masses Differences in air pressure are caused by unequal heating of Earth’s surface. The region along the equator receives more solar energy than the regions at the poles do. Conversely, cold air near the pole sinks and creates high-pressure centers. Differences in air pressure at different locations on Earth create wind patterns.

Chapter 24 Section 1 Air Masses How Air Moves Air moves from areas of high pressure to areas of low pressure. Therefore, there is a general, worldwide movement of surface air from the poles toward the equator. Temperature and pressure differences on Earth’s surface create three wind belts in the Northern Hemisphere and three wind belts in the Southern Hemisphere. The Coriolis effect, which occurs when winds are deflected by Earth’s rotation, also influences wind patterns.

Formation of Air Masses
Chapter 24 Section 1 Air Masses Formation of Air Masses air mass a large body of air throughout which temperature and moisture content are similar When air pressure differences are small, air remains relatively stationary. If air remains stationary or moves slowly over a uniform region, the air takes on characteristic temperature and humidity of that region. Air masses that form over frozen polar regions are very cold and dry. Air masses that form over tropical oceans are warm and moist.

Chapter 24 Types of Air Masses
Section 1 Air Masses Types of Air Masses Air masses are classified according to their source regions. The source regions for cold air masses are polar areas. The source regions for warm air masses are tropical areas. Air masses that form over the ocean are called maritime. Air masses that form over land are called continental. The combination of tropical or polar air and continental or maritime air results in air masses that have distinct characteristics.

Types of Air Masses, continued
Chapter 24 Section 1 Air Masses Types of Air Masses, continued Continental Air Masses There are two types of continental air masses: continental polar (cP) and continental tropical (cT). Continental polar air masses are cold and dry. Continental tropical air masses are warm and dry. An air mass may remain over its source region for days or weeks. However, the air mass will eventually move into other regions because of global wind patterns.

Chapter 24 Section 1 Air Masses Types of Air Masses, continued Maritime Air Masses When these very moist masses of air travel to a new location, they commonly bring more precipitation and fog. The two different maritime air masses are maritime polar (mP) and maritime tropical (mT). Maritime polar air masses are moist and cold. Maritime tropical air masses are moist and warm.

Chapter 24 Section 1 Air Masses Types of Air Masses, continued The diagram below shows the four types of air mass that influence North America.

North American Air Mass
Chapter 24 Section 1 Air Masses North American Air Mass The four types of air masses that affect the weather of North America come from six regions. An air mass usually brings the weather of its source region, but an air mass may change as it moves away from its source region. For example, cold, dry air may become warm and more moist as it moves from land to the warm ocean.

North American Air Mass, continued
Chapter 24 Section 1 Air Masses North American Air Mass, continued Tropical Air Mass Continental tropical air masses form over the deserts of the Southwestern United States. These air masses bring dry, hot weather in the summer. They do not form in the winter. Maritime tropical air masses form over the warm water of the tropical Atlantic Oceans. Maritime tropical air masses also form over the warm areas of the Pacific Oceans.

Chapter 24 Section 1 Air Masses Reading Check Which air mass brings dry, hot weather in the summer?

Chapter 24 Section 1 Air Masses Reading Check Which air mass brings dry, hot weather in the summer? a continental tropical air mass

Chapter 24 Section 1 Air Masses North American Air Mass, continued Polar Air Masses Polar air masses from three regions—northern Canada and the northern Pacific and Atlantic Oceans—influence weather in North America. In summer, the air masses usually bring cool, dry weather. In winter, they bring very cold weather to the northern United States.

Chapter 24 Section 1 Air Masses North American Air Mass, continued Polar Air Masses, continued Maritime polar air masses form over the North Pacific Ocean and are very moist, but they are not as cold as continental polar Canadian air masses. In winter, these maritime polar Pacific air masses bring rain and snow to the Pacific Coast. In summer, they bring cool, often foggy weather.

Chapter 24 Section 1 Air Masses North American Air Mass, continued Polar Air Masses, continued Maritime polar Atlantic air masses move generally eastward toward Europe. But they sometimes move westward over New England and eastern Canada. In winter, they can bring cold, cloudy weather and snow. In summer, these air masses can produce cool weather, low clouds, and fog.

Chapter 24 Air Masses Section 1 Air Masses
Click below to watch the Visual Concept. Visual Concept

Chapter 24 Section 2 Fronts Objectives Compare the characteristic weather patterns of cold fronts with those of warm fronts. Describe how a midlatitude cyclone forms. Describe the development of hurricanes, thunderstorms, and tornadoes.

Chapter 24 Section 2 Fronts Fronts A cool air mass is dense and does not mix with the less-dense air of a warm air mass. Thus, a boundary, called a front, forms between air masses. Changes in middle-latitude weather usually take place along the various types of fronts. Fronts do not exist in the Tropics because no air masses that have significant temperature differences exist there.

Chapter 24 Fronts, continued Cold Fronts
Section 2 Fronts Fronts, continued Cold Fronts cold front the front edge of a moving mass of cold air that pushes beneath a warmer air mass like a wedge If the warm air is moist, clouds will form.

Chapter 24 Fronts, continued Cold Fronts, continued
Section 2 Fronts Fronts, continued Cold Fronts, continued Large cumulus and cumulonimbus clouds typically form along fast-moving cold fronts. A long line of heavy thunderstorms, called a squall line, may occur in the warm, moist air just ahead of a fast-moving cold front. A slow-moving cloud front typically produces weaker storms and lighter precipitation than a fast-moving cold front does.

Chapter 24 Fronts, continued Warm Fronts
Section 2 Fronts Fronts, continued Warm Fronts warm front the front edge of advancing warm air mass that replaces colder air with warmer air The slope of a warm front is gradual. Because of this gentle slope, clouds may extend far ahead of the surface location, or base, of the front. A warm front generally produces precipitation over a large area and may cause violent weather.

Chapter 24 Fronts, continued Stationary and Occluded Fronts
Section 2 Fronts Fronts, continued Stationary and Occluded Fronts stationary front a front of air masses that moves either very slowly or not at all occluded front a front that forms when a cold air mass overtakes a warm air mass and lifts the warm air mass of the ground and over another air mass Sometimes, when air masses meet, the cold moves parallel to the front, and neither air mass is displaced.

Polar Fronts and Midlatitudes Cyclones
Chapter 24 Section 2 Fronts Polar Fronts and Midlatitudes Cyclones Over each of Earth’s polar regions is a dome of cold air that may extend as far as 60° latitude. The boundary where this cold polar air meets the tropical air mass of the middle latitudes, especially over the ocean, is called the polar front. Waves commonly develop along the polar front. A waves is a bend that forms in a cold front or stationary front.

Polar Fronts and Midlatitudes Cyclones, continued
Chapter 24 Section 2 Fronts Polar Fronts and Midlatitudes Cyclones, continued midlatitude cyclone an area of low pressure that is characterized by rotating wind that moves toward the rising air of the central low-pressure region Waves are the beginnings of low-pressure storm centers called midlatitude cyclones or wave cyclones. These cyclones strongly influence weather patterns in the middle latitudes.

Chapter 24 Section 2 Fronts Polar Fronts and Midlatitudes Cyclones, continued Stages of a Midlatitude Cyclones A midlatitude cyclone usually last several days. In North America, midlatitude cyclones generally travel about 45 km/h in an easterly direction as they spin counterclockwise. They follow several storm tracks, or routes, as they move from the Pacific coast to the Atlantic coast.

Chapter 24 Section 2 Fronts Polar Fronts and Midlatitudes Cyclones, continued The diagram below shows the different stages of a midlatitude cyclone.

Chapter 24 Section 2 Fronts Polar Fronts and Midlatitudes Cyclones, continued Anticyclones Unlike the air in the midlatitude cyclone, the air of an anticyclone sinks and flows outward from a center of high pressure. Because of the Coriolis effect, the circulation of air around an anticyclone is clockwise in the Northern Hemisphere. Anticyclones bring dry weather, because their sinking air does not promote cloud formation.

Chapter 24 Section 2 Fronts Reading Check How is the air of an anticyclone different from that of a midlatitude cyclone?

Chapter 24 Section 2 Fronts Reading Check How is the air of an anticyclone different from that of a midlatitude cyclone? The air of an anticyclone sinks and flows outward from a center of high pressure. The air of a midlatitude cyclone rotates toward the rising air of a central, low-pressure region.

Chapter 24 Severe Weather Thunderstorms
Section 2 Fronts Severe Weather Thunderstorms thunderstorm a usually brief, heavy storm that consists of rain, strong winds, lightning, and thunder Thunderstorms develop in three distinct stages. The thunderstorm dissipates as the supply of water vapor decrease.

Severe Weather, continued
Chapter 24 Section 2 Fronts Severe Weather, continued Lightning During a thunderstorm, clouds discharge electricity in the form of lightning. The released electricity heats the air, and the air rapidly expands and produces a loud noise known as thunder. For lightning to occur, the clouds must have areas that carry distinct electrical charges.

Chapter 24 Section 2 Fronts Severe Weather, continued Hurricanes hurricane a severe storm that develops over tropical oceans and whose strong winds of more than 120 km/h spiral in toward the intensely low-pressure storm center A hurricane begins when warm, moist air over the ocean rises rapidly. When moisture in the rising warm air condenses, a large amount of energy in the from of latent heat is released. This heat increase the force of the rising air.

Chapter 24 Section 2 Fronts Severe Weather, continued Hurricanes, continued A fully developed hurricane consists of a series of thick cumulonimbus cloud bands that spiral upward around the center of the storm. The most dangerous aspect of a hurricane is a rising sea level and large waves, called a storm surge. Every hurricane is categorized on the Safir-Simpson scale by using several factors. These factors include central pressure, wind speed, and storm surge.

Chapter 24 Section 2 Fronts Reading Check Where do hurricanes develop?

Chapter 24 Reading Check Where do hurricanes develop?
Section 2 Fronts Reading Check Where do hurricanes develop? over warm tropical seas

Chapter 24 Section 2 Fronts Severe Weather, continued Tornadoes tornado a destructive, rotating column of air that has very high wind speeds and that maybe visible as a funnel-shaped cloud The smallest, most violent, and shortest-lived severe storm is a tornado. A tornado forms when a thunderstorm meets high-altitude horizontal winds. These winds cause the rising air in the thunderstorm to rotate.

Chapter 24 Section 2 Fronts Severe Weather, continued Tornadoes, continued A storm cloud may develop a narrow, funnel-shaped rapidly spinning extension that reaches downward and may or may not touch the ground. If the funnel does touch the ground, it generally moves in a wandering, haphazard path. The destructive power of a tornado is due to mainly the speed of the winds. These winds may reach speeds of more than 400 km/h.

Chapter 24 Types of Fronts Section 2 Fronts

Chapter 24 Section 3 Weather Instruments Objectives Identify four instruments that measure lower-atmospheric weather conditions. Describe how scientists measure conditions in the upper atmosphere. Explain how computers help scientists understand weather.

Measuring Lower-Atmospheric Conditions
Chapter 24 Section 3 Weather Instruments Measuring Lower-Atmospheric Conditions Air Temperature thermometer an instrument that measures and indicates temperature A common type of thermometer uses a liquid—usually mercury or alcohol—sealed in a glass tube to indicate temperature. A rise in temperature causes the liquid to expand and fill more of the tube. A drop in temperature causes the liquid to contract and fill less of the tube.

Measuring Lower-Atmospheric Conditions, continued
Chapter 24 Section 3 Weather Instruments Measuring Lower-Atmospheric Conditions, continued Air Temperature, continued Another type of thermometer is an electrical thermometer. As the temperature rises, the electric current that flows through the material of the electrical thermometer increases and is translated into temperature readings. A thermistor, or thermal resistor, is a type of electrical thermometer that responds very quickly to temperature changes.

Chapter 24 Section 3 Weather Instruments Measuring Lower-Atmospheric Conditions, continued Air Pressure barometer an instrument that measures atmospheric pressure Changes in air pressure affect air masses. The approach of a front is usually indicated by a drop in air pressure.

Chapter 24 Section 3 Weather Instruments Measuring Lower-Atmospheric Conditions, continued Wind Speed anemometer an instrument used to measure wind speed A typical anemometer consists of small cups that are attached by spokes to a shaft that rotates freely. The wind pushes against the cup and causes them to rotate. This rotation triggers an electrical signal that registers the wind speed in meters per second or in miles per hour.

Chapter 24 Section 3 Weather Instruments Measuring Lower-Atmospheric Conditions, continued Wind Direction wind vane an instrument used to determine direction of the wind The wind vane is commonly an arrow-shaped device that turns freely on a pole as the tail catches the wind. Wind direction may be described by using one of 16 compass directions, such as north-northeast. Wind direction also may be recorded in degrees by moving clockwise and beginning with 0° at the north.

Chapter 24 Section 3 Weather Instruments Reading Check Which instrument is used to measure air pressure?

Chapter 24 Section 3 Weather Instruments Reading Check Which instrument is used to measure air pressure? A barometer is used to measure atmospheric pressure.

Measuring Upper-Atmospheric Conditions
Chapter 24 Section 3 Weather Instruments Measuring Upper-Atmospheric Conditions Radiosonde radiosonde a package of instruments that is carried aloft by balloons to measure upper atmospheric conditions, including temperature, dew point, and wind velocity The radiosonde sends measurements as radio waves to a receiver that records the information. When the balloon reaches a very high altitude, the balloon expands and bursts, and the radiosonde parachutes back to Earth.

Measuring Upper-Atmospheric Conditions, continued
Chapter 24 Section 3 Weather Instruments Measuring Upper-Atmospheric Conditions, continued Radar radar radio detection and ranging, a system that uses reflected radio waves to determine the velocity and location of objects For example, large particles of water in the atmosphere reflect radar pulses. The newest Doppler radar can indicate the precise location, movement,and extent of a storm. It can also indicate the intensity of precipitation and wind patterns within a storm.

Chapter 24 Section 3 Weather Instruments Measuring Upper-Atmospheric Conditions, continued Weather Satellites Satellite images provide weather information for regions where observations cannot be made from ground. The direction and speed of the wind at the level of the clouds can also be measured by examining a continuous sequence of cloud images. Satellite instruments can also measure marine conditions.

Chapter 24 Section 3 Weather Instruments Measuring Upper-Atmospheric Conditions, continued Computers Before computers were available, solving the mathematical equations that describe the behavior of the atmosphere was very difficult, and sometimes impossible. In addition to solving many of these equations, computers can store weather data from around the world. These data can provide information that is useful in forecasting weather changes.

Collecting Weather Data in the Upper Atmosphere
Chapter 24 Section 3 Weather Instruments Collecting Weather Data in the Upper Atmosphere Click below to watch the Visual Concept. Visual Concept

Chapter 24 Section 4 Forecasting the Weather Objectives Explain how weather stations communicate weather data. Explain how a weather map is created. Explain how computer models help meteorologists forecast weather. List three types of weather that meteorologists have attempted to control.

Global Weather Monitoring
Chapter 24 Section 4 Forecasting the Weather Global Weather Monitoring Weather stations around the world exchange the weather information they have collected. The World Meteorological Organization (WMO) sponsors a program called World Weather Watch to promote the rapid exchange of weather information. It also offers advice on the effect of weather on natural resource and on human activities, such as farming and transportation.

Chapter 24 Weather Maps Weather Symbols
Section 4 Forecasting the Weather Weather Maps Weather Symbols station model a pattern of meteorological symbols that represent the weather at a particular observing station and that is recorded on a weather map Common weather symbols describe cloud cover, wind speed, wind direction, and weather conditions, such as type of precipitation and storm activity.

Weather Maps, continued
Chapter 24 Section 4 Forecasting the Weather Weather Maps, continued Weather Symbols, continued Other information included in the station model are the air temperature and the dew point. The dew point indicates how high the humidity of the air is, or how much water is in the air. The station model also indicates the atmospheric pressure by using a three-digit number in the upper right hand corner.

Chapter 24 Section 4 Forecasting the Weather Weather Maps, continued The diagram below shows the different weather symbols used on weather maps.

Chapter 24 Section 4 Forecasting the Weather Weather Maps, continued Plotting Temperature and Pressure Lines that connect points of equal temperatures are called isotherms. Lines that connect points of equal atmospheric pressure are called isobars. The spacing and shape of the isobars help meteorologists interpret their observations about the speed and direction of the wind.

Chapter 24 Section 4 Forecasting the Weather Weather Maps, continued Plotting Fronts and Precipitation Most weather maps mark the locations of fronts and areas of precipitation. Fronts are identified by sharp changes in wind speed and direction, temperature or humidity. Areas of precipitation are commonly marked by using colors or symbols.

Chapter 24 Section 4 Forecasting the Weather Weather Maps, continued The diagram below shows an example of a typical weather map.

Chapter 24 Section 4 Forecasting the Weather Reading Check How do meteorologists mark precipitation on a weather map?

Chapter 24 Section 4 Forecasting the Weather Reading Check How do meteorologists mark precipitation on a weather map? Areas of precipitation are marked by using colors or symbols.

Chapter 24 Weather Forecasts
Section 4 Forecasting the Weather Weather Forecasts To forecast the weather, meteorologists regularly plot to the intensity and path of weather systems on maps. Meteorologists then study the must recent weather map and compare it with maps from previous hours. By following the progress of weather systems, meteorologist can forecast the weather.

Weather Forecasts, continued
Chapter 24 Section 4 Forecasting the Weather Weather Forecasts, continued Weather Data Computers models can show the possible weather conditions for several days. Comparing models helps meteorologists better predict weather. By using computers, scientists can manipulate data on temperature and pressure to simulate errors in measuring these data.

Chapter 24 Reading Check Why do meteorologists compare models.
Section 4 Forecasting the Weather Reading Check Why do meteorologists compare models.

Chapter 24 Reading Check Why do meteorologists compare models.
Section 4 Forecasting the Weather Reading Check Why do meteorologists compare models. Meteorologists compare computer models because different models are better at predicting different weather variables. If information from two or more models matches, scientists can be more confident of their predictions.

Chapter 24 Section 4 Forecasting the Weather Weather Forecasts, continued Types of Forecasts Meteorologists make four types of forecasts. Daily forecasts predict weather conditions for a 48-hour period. Extended forecasts look ahead 3 to 7 days. Medium range forecasts look ahead 8 to 14 days. Long-range forecasts cover monthly and seasonal periods. Accurate weather forecasts can be made for 0 to 7 days. However, accuracy decreases with each day.

Chapter 24 Section 4 Forecasting the Weather Weather Forecasts, continued Severe Weather Watches and Warnings One main goal of meteorology is to reduce the amount of destruction caused by severe weather by forecasting severe weather early. A watch is issued when the conditions are ideal for severe weather. A warning is given when severe weather has been spotted or is expected within 24 hours.

Controlling the Weather
Chapter 24 Section 4 Forecasting the Weather Controlling the Weather Some meteorologists are investigating methods of controlling rain, hail, and lightning. Currently, the most researched method for producing rain has been cloud seeding. Cloud seeding can also be used to prevent more severe precipitation.

Controlling the Weather, continued
Chapter 24 Section 4 Forecasting the Weather Controlling the Weather, continued Hurricane Control Hurricanes have also been seeded with freezing nuclei in an effort to reduce the intensity of the storm. During Project Stormfury, which took place from 1962 to 1983, four hurricanes were seeded, and the project had mixed results. Scientists have, for the most part, abandoned storm and hurricane control because it is not an attainable goal with existing technology.

Controlling the Weather, continued
Chapter 24 Section 4 Forecasting the Weather Controlling the Weather, continued Lightning Control Seeding of potential lightning storms with silver-iodide nuclei has seemed to modify the occurrence of lighting. However, no conclusive results have been obtained.

Chapter 24 Isobar Section 4 Forecasting the Weather

Chapter 24 Weather Brain Food Video Quiz

Chapter 24 Maps in Action Maps in Action
Weather-Related Disasters, 1980–2003

Chapter 24 Multiple Choice
Standardized Test Prep Multiple Choice 1. What tool do meteorologists use to analyze particle movements within storms? A. an anemometer B. a radiosonde balloon C. doppler radar D. satellite imaging

Multiple Choice, continued
Chapter 24 Standardized Test Prep Multiple Choice, continued 1. What tool do meteorologists use to analyze particle movements within storms? A. an anemometer B. a radiosonde balloon C. doppler radar D. satellite imaging

Chapter 24 Standardized Test Prep Multiple Choice, continued 2. What kind of front forms when two air masses move parallel to the boundary located between them? F. an occluded front G. a polar front H. a warm front I. a stationary front

Chapter 24 Standardized Test Prep Multiple Choice, continued 3. Which of the following weather systems commonly forms over warm tropical oceans? A. thunderstorms B. hurricanes C. tornadoes D. anticyclones

Chapter 24 Standardized Test Prep Multiple Choice, continued 4. What often happens to maritime air masses as they move inland over mountainous country? F. They bring warm, dry weather conditions. G. They produce clouds and hurricanes. H. They bring cold, dry weather conditions. I. They lose moisture passing over mountains.

Chapter 24 Standardized Test Prep Multiple Choice, continued 5. What type of air mass originates over the south- weathern desert of the United States in summer? A. continental polar air mass B. continental tropical air mass C. maritime polar air mass D. maritime tropical air mass

Chapter 24 Short Response
Standardized Test Prep Short Response 6. What type of front is formed when a warm air mass is overtaken by a cold air mass, which causes the warm air to lift above the cold air?

Short Response, continued
Chapter 24 Standardized Test Prep Short Response, continued 6. What type of front is formed when a warm air mass is overtaken by a cold air mass, which causes the warm air to lift above the cold air? Cold front

Chapter 24 Standardized Test Prep Short Response, continued 7. What do closely spaced isobars indicate about the wind on a weather map?

Chapter 24 Standardized Test Prep Short Response, continued 7. What do closely spaced isobars indicate about the wind on a weather map? high-speed winds

Chapter 24 Reading Skills Standardized Test Prep Tornado Alley
Read the passage below. Then, answer questions 8–10. Tornado Alley Though tornadoes are not unique to the area, the violent, rotating, funnel-shaped clouds and their trails of destruction are so common in the central United States that the area is called Tornado Alley. These severe thunderstorms and the super-cell tornadoes that they spawn are formed when warm, moist air from the Gulf of Mexico becomes trapped beneath hot, dry air from the southwest desert region. Above that hot, dry air, cold, dry air sweeps in from the Rocky Mountains. The interaction between high-altitude winds and thunderstorms creates the funnel-shaped vortex of high-speed winds known as a tornado. The largest outbreak of tornadoes in this region occurred in April of Before the storms ended, 148 separate tornadoes roared through 13 different states. More than 300 people lost their lives, and another 5,000 people were injured. More than 1,300 buildings were destroyed.

Reading Skills, continued
Chapter 24 Standardized Test Prep Reading Skills, continued 8. Why is the central part of the United States also known as Tornado Alley? A. Tornadoes in the area move in straight lines known as alleys. B. The destruction left by tornadoes made the area look like an unkempt alley. C. Areas between buildings are the safest places to be during a tornado. D. Tornadoes are common occurrences in this particular part of the country.

Chapter 24 Standardized Test Prep Reading Skills, continued 9. Which of the following statements can be inferred from the information in the passage? F. In the United States, tornadoes are more common in some areas than in other areas. G. Tornadoes can form only in the area near the Rocky Mountains. H. All tornadoes cause injuries to humans. I. Multiple tornadoes are a rare occurrence.

Chapter 24 Standardized Test Prep Reading Skills, continued 10. What makes tornadoes so much more difficult to predict than other severe weather systems?

Chapter 24 Standardized Test Prep Reading Skills, continued 10. What makes tornadoes so much more difficult to predict than other severe weather systems? Tornadoes are difficult to predict because they form suddenly from unstable conditions.

Interpreting Graphics
Chapter 24 Standardized Test Prep Interpreting Graphics Use the diagram below to answer questions 11 and 12. The diagram shows a station model.

Interpreting Graphics, continued
Chapter 24 Standardized Test Prep Interpreting Graphics, continued 11. What letter represents the current barometric reading shown in the model? A. letter A B. letter B C. letter C D. letter D

Chapter 24 Standardized Test Prep Interpreting Graphics, continued 12. What weather information do the symbols indicated by the letters E and F provide? Interpret this part of the station model.

Chapter 24 Standardized Test Prep Interpreting Graphics, continued 12. What weather information do the symbols indicated by the letters E and F provide? Interpret this part of the station model. E is wind direction, and F is wind speed. Currently, the station model is showing a 30-knot wind that is blowing in from south.

Chapter 24 Standardized Test Prep Interpreting Graphics, continued Use the diagram below to answer questions 13 and 14. The diagram shows a home weather station.

Chapter 24 Standardized Test Prep Interpreting Graphics, continued 13. Which of the following weather instruments shown uses the cooling effect of evaporation to take measurements. A. a rain gauge B. a psychrometer C. a wind sock D. a thermometer

Chapter 24 Standardized Test Prep Interpreting Graphics, continued 14. Describe how an anemometer is used to calculate wind speed.

Chapter 24 Standardized Test Prep Interpreting Graphics, continued 14. Describe how an anemometer is used to calculate wind speed. Answers should include: as the cups on the anemometer catch the wind, the device begins to rotate; the speed of this rotation, usually given in revolutions per minute, and the circumference of the circle made by the cups are used to calculate wind speed; rudimentary devices rely on the user to count the revolutions per minute of the device and to perform the necessary math to determine the wind speed; in modern computerized devices, a number of factors may be considered to obtain the most accurate measurement possible, including the circumference of the device, friction of the air, and drag.

Chapter 24 Air Masses

Stages of a Midlatitude Cyclone
Chapter 24 Stages of a Midlatitude Cyclone

Chapter 24 Weather Symbols

Weather Map of the United States
Chapter 24 Weather Map of the United States

Weather-Related Disasters, 1980-2003
Chapter 24 Weather-Related Disasters,

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