1. Unit 4 Weather Lesson 3 How is Weather Predicted?

2. Measuring Weather  The study of weather is meteorology.  Meteorologists are people who study weather. Weather instruments, wind direction, and clouds can help make weather predictions.

3. Thermometer  Measures air temperature  Air cools down during the day or warms up at night → rain may fall soon.

4. Barometer  Measures air pressure  Also called barometric pressure  Change in air pressure →change in weather

5. Anemometer  Measures wind speed  Change in wind speed → change in weather

6. Hygrometer  Measures humidity  Increased humidity → about to rain

7. Air Masses  Air moves in an air mass, a large body of air that has the same temperature and humidity throughout.  Air masses may be warm or cold and humid or dry.

8. Four Kinds of Air Masses that Affect Weather in the United States  Continental polar (cP) – cool, dry weather  Continental tropical (cT) – hot, dry weather  Maritime polar (mP) – cold, humid weather  Maritime tropical (mT) – warm, humid weather

9. Warm Front  Forms where a warm air mass moves over a cold air mass.  As this happens, stratus clouds form. stratus clouds form.  They produce rain or snow that can last for hours.  After a warm front passes through an area, the weather is warmer and more humid.

10. Cold Front  After a cold front passes through an area, the weather is cooler and drier.  Forms where a cold air mass moves under a warm air mass.  The warm air is pushed up and cooled.  This fast cooling and condensation causes heavy rains, thunderstorms, or snow.  Cold fronts move quickly, so these storms do not last long.

11. Weather Maps  Weather maps use symbols to show the weather.  A weather map can also give information about temperature.

12. Weather Symbols

13. Forecasting Weather  Meteorologists make weather forecasts based on data from weather stations, weather satellites and special weather instruments.

14. Variables that Affect Weather Forecasts  Wind direction – Example: weather blowing from the north will soon reach your area  Air pressure – low-pressure: stormy weather; low-pressure: stormy weather; high-pressure: fair weather high-pressure: fair weather

15. Videos on Weather How to Predict Weather http://www.youtube.com/watch?v=YxH1xiNirhA Fronts http://www.youtube.com/watch?v=vPC5i6w3yDI&feature=related Weather for Kids part 1 (15:00) http://www.youtube.com/watch?v=v1-Khi9i3UU&feature=related Weather for Kids part 2 (12:09) http://www.youtube.com/watch?v=IbRln1GIOdA&feature=related