1. Chapter 25 Modern Earth Science
Weather
Chapter 25
Modern Earth Science
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2. Chapter 25 Section 3 Modern Earth Science
Weather Instruments
Chapter 25
Section 3
Modern Earth Science

3. Essential Question
Identify four instruments that measure lower-atmospheric weather conditions and describe how scientists measure conditions in the upper atmosphere.

4. Weather Instruments Barometer: measures air pressure. (chapter 23)
Psychrometers & hair hygrometers : measure relative humidity. (ch 24)
Rain gauge: measures precipitation. (chapter 24)

5. Measuring Air Temperature
Thermometer: used to measure air temperature.
3 common types of thermometers
Liquid: expanding & contracting mercury or alcohol indicate rise or fall of temperature.
Bimetal: made of 2 strips of metal that bend when heated.
Electrical: as temp rises, electrical current increases.

6. Measuring Wind Speed & Direction
Anemometer: measures wind speed
Wind vane: indicates wind direction.

7. Measuring Upper-Atmospheric Conditions
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.

8. Measuring Upper-Atmospheric Conditions, continued
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.

9. 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.

10. 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.