1. Predicting the Weather
Section 4
Pages

2. Who is the weather forecast important to?
Farmers
Pilots
People with plans… headed to the park, going to watch the Tigers, have a softball game
People that work outside
It is also the topic of many conversations

3. Weather Forecasting
Based on observations, what predictions can you make about the weather?
You could read a barometer. If the air pressure is falling, rain or snow could be on its way.
Read the clouds. Cumulonimbus clouds may bring a thunderstorm. Cirrus clouds high in the sky mean low pressure area may be approaching.

4. Meteorologists
Meteorologists are scientists who study the causes of weather and try to predict it.

5. Sources of information
Where do meteorologists get weather information?
Local weather observers (like you!)
Instruments carried by balloons
Satellites
Weather stations around the world
Radar (tracks precipitation)

6. Weather Technology
Meteorologists can make long-range predictions because of changes in technology.
Changes have occurred in two areas:
Gathering weather data
(weather balloons, satellites)
Using computers

7. How are computers used to help forecast weather?
Computer Forecasts
How are computers used to help forecast weather?
Instruments gather thousands of bits of data
Computers process the information.
Computer makes calculations
for forecasts.
Each forecast builds on
previous forecasts.

8. El Nino
Some long-term weather patterns may be caused by changes in ocean currents and global winds.
El Nino, a warm-water event, occurs in the tropical Pacific Ocean once every 2-7 years.
Warm water replaces cold water.

9. Weather Service Maps
Data from more than 300 local weather stations all over the country are assembled into weather maps at the National Weather Service.

10. Weather Service Maps
A typical reporting weather station provides you with the following data:
temperature
precipitation
wind speed and direction
atmospheric pressure
cloud cover

11. Interpreting Data
Use the key to Figure 19 (on page 103) to help you answer the questions about this weather station data.

12. Isobars
Isobars are (curvy) lines joining places on the map that have the same air pressure.
Iso means “equal” and bar means “pressure”.
Air pressure readings can be given in inches of mercury, in millibars, or both.

13. Isotherms
Isotherms are (curvy) lines joining places that have the same temperature.
The isotherm may be labeled with the temperature in degrees Fahrenheit, degrees Celsius, or both.

14. Newspaper Weather Maps
Maps in newspapers are simplified versions of the maps produced by the National Weather Service.
Standard symbols on weather maps show:
fronts
temperature
pressure
types of precipitation

15. The Butterfly Effect
A forecast for the weather six days from now is based on forecasts for all the days between now and then.
A small change in the weather today can mean a larger change in the weather a week later.
Why would you call this the butterfly effect?

16. Words Worth Knowing (ISN #29)
Meteorologist
El Nino
Isobars
Isotherms