Objectives State the importance of accurate weather data. Section 12.3 Gathering Weather Data Objectives State the importance of accurate weather data. Summarize the instruments used to collect weather data from Earth’s surface. Analyze the strengths and weaknesses of weather radar and weather satellites.

Section 12.3 Gathering Weather Data Accurate measurements of atmospheric properties are a critical part of weather analysis and prediction. Review Vocabulary temperature: the average thermal energy of the particles that make up a substance

New Vocabulary Gathering Weather Data thermometer barometer anemometer Section 12.3 Gathering Weather Data New Vocabulary thermometer barometer anemometer hygrometer radiosonde Doppler effect

Data from Earth’s Surface Section 12.3 Gathering Weather Data Data from Earth’s Surface Two important factors in weather forecasting are the accuracy of the data and the amount of available data.

Data from Earth’s Surface Section 12.3 Gathering Weather Data Data from Earth’s Surface Temperature and air pressure A thermometer measures temperature using either the Fahrenheit or Celsius scale. A barometer measures air pressure.

Data from Earth’s Surface Section 12.3 Gathering Weather Data Data from Earth’s Surface Wind speed and relative humidity An anemometer measures wind speed. A hygrometer measures relative humidity.

Data from Earth’s Surface Section 12.3 Gathering Weather Data Data from Earth’s Surface Automated Surface Observing System The Automated Surface Observing System (ASOS) gathers data in a consistent manner, 24 hours a day, every day. It provides essential weather data for aviation, weather forecasting, and weather-related research.

Data from the Upper Atmosphere Section 12.3 Gathering Weather Data Data from the Upper Atmosphere The instrument used for gathering upper-atmosphere data is a radiosonde. A radiosonde’s sensors measure the air’s temperature, pressure, and humidity. Also wind speed and direction( by its movement)

Weather Observation Systems Section 12.3 Gathering Weather Data Weather Observation Systems Weather radar A weather radar system detects specific locations of precipitation. The Doppler effect is the change in pitch or frequency that occurs due to the relative motion of a wave, such as sound or light, as it comes toward or goes away from an observer.

Weather Observation Systems Section 12.3 Gathering Weather Data Weather Observation Systems Doppler radar Analysis of Doppler radar data can be used to determine the speed at which precipitation moves toward or away from a radar station.

Difference between radar and Doppler radar. detects specific locations of precipitation. speed at which precipitation moves toward or away from a radar station.

Weather Observation Systems Section 12.3 Gathering Weather Data Weather Observation Systems Weather satellites -3 types of imaging Infra red, 2. visible light, 3.water vapor imagery. Some satellites use cameras that require visible light to photograph Earth. These digital photos are sent back to ground stations, and their data are plotted on maps. Unlike weather radar, which tracks precipitation but not clouds, satellites track clouds but not necessarily precipitation.

Weather Observation Systems Section 12.3 Gathering Weather Data Weather Observation Systems Weather satellites track clouds and water vapor. Some weather satellites use infrared imagery to make observations at night. Objects radiate thermal energy at slightly different frequencies. Infrared imagery detects these different frequencies, which enables meteorologists to map either cloud cover or surface temperatures.

Weather Observation Systems Section 12.3 Gathering Weather Data Weather Observation Systems Weather satellites Another type of satellite imagery that is useful in weather analysis and forecasting is called water-vapor imagery. Water-vapor imagery is a valuable tool for weather analysis and prediction because it shows moisture in the atmosphere, not just cloud patterns.

Difference between weather radar and weather satellite Tracks precipitation Tracks clouds and moisture.

Objectives Review Vocabulary Analyze a basic surface weather chart. Section 12.4 Weather Analysis and Prediction Objectives Analyze a basic surface weather chart. Distinguish between digital and analog forecasting. Describe problems with long-term forecasts. Review Vocabulary model: an idea, system, or mathematical expression that represents an idea

Section 12.4 Weather Analysis and Prediction Several methods are used to develop short-term and long-term weather forecasts. New Vocabulary station model isobar isotherm digital forecast analog forecast

Surface Weather Analysis Section 12.4 Weather Analysis and Prediction Surface Weather Analysis Station models A station model is a record of weather data for a particular site at a particular time.

Surface Weather Analysis Section 12.4 Weather Analysis and Prediction Surface Weather Analysis Station models Meteorological symbols are used to represent weather data in a station model. Advantages: universal language, more info in less space.

Surface Weather Analysis Section 12.4 Weather Analysis and Prediction Surface Weather Analysis Plotting station model data To plot data nationwide and globally, meteorologists use lines that connect points of equal or constant values.

Surface Weather Analysis Section 12.4 Weather Analysis and Prediction Surface Weather Analysis Plotting station model data Lines of equal pressure are called isobars. Lines of equal temperature are called isotherms.

Surface Weather Analysis Section 12.4 Weather Analysis and Prediction Surface Weather Analysis Interpreting station model data The weather map shows isobars and air pressure data for the continental United States.

Surface Weather Analysis Section 12.4 Weather Analysis and Prediction Surface Weather Analysis Interpreting station model data Using isobars, isotherms, and station model data, meteorologists can analyze current weather conditions for a particular location.

Types of Forecasts Digital forecasts Section 12.4 Weather Analysis and Prediction Types of Forecasts Digital forecasts A digital forecast is created by applying physical principles and mathematics to atmospheric variables and then making a prediction about how these variables will change over time.

Types of Forecasts Analog forecasts Section 12.4 Weather Analysis and Prediction Types of Forecasts Analog forecasts An analog forecast is based on a comparison of current weather patterns to similar weather patterns from the past.

Differences between digital and analog forecasts. By analyzing current weather data By comparing current weather patterns with similar patterns from the past.

Section 12.4 Weather Analysis and Prediction Short-Term Forecasts The most accurate and detailed forecasts are short term because weather systems change directions, speeds, and intensities over time.

Section 12.4 Weather Analysis and Prediction Long-Term Forecasts Because it is impossible for computers to model every variable that affects the weather at a given time and place, all long-term forecasts are less reliable than short-term forecasts. Short term forecasts are more reliable.

Section 12.3 Gathering Weather Data Study Guide Key Concepts Section 12.3 Gathering Weather Data Accurate measurements of atmospheric properties are a critical part of weather analysis and prediction. To make accurate weather forecasts, meteorologists analyze and interpret data gathered from Earth’s surface by weather instruments.

Section 12.3 Gathering Weather Data Study Guide Key Concepts Section 12.3 Gathering Weather Data A radiosonde collects upper-atmospheric data. Doppler radar locates where precipitation occurs. Weather satellites use infrared, visible-light, or water-vapor imagery to observe and monitor changing weather conditions on Earth.

Section 12.4 Weather Analysis and Prediction Study Guide Key Concepts Section 12.4 Weather Analysis and Prediction Several methods are used to develop short-term and long-term weather forecasts. A station model is used to plot different weather variables. Meteorologists plot lines on a map that connect variables of equal value to represent nationwide and global trends.

Section 12.4 Weather Analysis and Prediction Study Guide Key Concepts Section 12.4 Weather Analysis and Prediction Two kinds of forecasts are digital and analog. The longer the prediction period, the less reliable the weather forecast.

12 Meteorology Which weather instrument is used to measure wind speed? 12.3 Section Questions Which weather instrument is used to measure wind speed? a. barometer b. thermometer c. anemometer d. hygrometer

12 Meteorology 12.3 Section Questions Doppler radar data show that the return echo from one side of a storm has a shorter wavelength than the emitted wave. What can be concluded about the reflecting particles? a. They are very small. b. They are very large. c. They are moving toward the station. d. They are moving away from the station.

12 Meteorology Why are weather satellites important to forecasters? 12.3 Section Questions Why are weather satellites important to forecasters?

12 Meteorology 12.3 Section Questions Answer: Satellites can monitor weather conditions over large regions of Earth using a variety of wavelengths. The satellites provide information about cloud cover, moisture, atmospheric circulation, and more, which can be used together to provide current and rapid forecasts.

12 Meteorology What is an isobar? a. a line of constant altitude 12.4 Section Questions What is an isobar? a. a line of constant altitude b. a line of constant temperature c. a line of constant pressure d. a line of constant moisture

12 Meteorology Which weather forecast is usually the most accurate? 12.4 Section Questions Which weather forecast is usually the most accurate? a. one-day forecast b. three-day forecast c. seven-day forecast d. thirty-day forecast

12 Meteorology How are digital forecasts made? 12.4 Section Questions How are digital forecasts made? Possible answer: Digital forecasts are made by using computers to model future weather conditions based on current weather data.

Chapter Assessment Questions 12 Meteorology Chapter Assessment Questions What characteristics describe a continental tropical air mass? a. cool and dry b. hot and dry c. mild and humid d. hot and humid

Chapter Assessment Questions 12 Meteorology Chapter Assessment Questions A high-pressure system has moved directly over a region. What weather condition most likely exists in this region? a. fair weather b. steady rain c. high winds d. thunderstorms

Chapter Assessment Questions 12 Meteorology Chapter Assessment Questions Which type of wave is transmitted by weather radar units? a. X rays b. sound waves c. radio waves d. infrared waves

Chapter Assessment Questions 12 Meteorology Chapter Assessment Questions Examine the isobar map. From approximately which direction is the wind blowing in central Ohio? a. southwest b. southeast c. northwest d. northeast

Chapter Assessment Questions 12 Meteorology Chapter Assessment Questions A warm, moist air mass is currently over a region. What changes will occur as a strong cold front advances over this region?

Chapter Assessment Questions 12 Meteorology Chapter Assessment Questions Answer: The front has a high temperature contrast across it and a supply of moisture in front of it. As the cold front advances, uplift of moisture-laden air will occur and thunderstorms will probably develop. Some of these storms could be severe.

Standardized Test Practice 12 Meteorology Standardized Test Practice Which type of air mass forms over the Gulf of Mexico and Caribbean Sea? a. continental polar b. continental tropical c. maritime polar d. maritime tropical

Standardized Test Practice 12 Meteorology Standardized Test Practice A frigid, winter air mass is moving south across the central United States. Which feature can most modify the characteristics of this air mass? a. a large lake b. tree-covered hills c. snow-covered plains d. a lowland area

Standardized Test Practice 12 Meteorology Standardized Test Practice Which winds converge and rise at the intertropical convergence zone? a. polar easterlies b. westerlies c. trade winds d. jet streams

Standardized Test Practice 12 Meteorology Standardized Test Practice How is the path of a moving current of air in the southern hemisphere affected by Earth’s rotation? a. It curves to the right. b. It curves to the left. c. It curves upward. d. It curves downward.

Standardized Test Practice 12 Meteorology Standardized Test Practice How does the polar jet stream affect weather in the midlatitudes?

Standardized Test Practice 12 Meteorology Standardized Test Practice Possible answer: The jet stream marks the boundary between colder polar air and warmer subtropical air. Undulations in the jet stream move cold air to warmer latitudes and warm air to colder latitudes. Surface high- and low-pressure systems also form and move along the jet stream, so the jet stream guides weather across the midlatitudes.