Test---------- Friday, February 12, 2016
Science-----Chapter 6---lesson 3- Predicting Weather
Vocabulary Words
1. Weather Map- a map that shows the weather in a specific area at a specific time.
2. Isobar- a line on a weather map that connects places with equal air pressure.
3. Front- the boundary between two air masses.
4. Air mass- the large region of the atmosphere in which the air has similar properties.
Notes
1. How are the isobar lines drawn on a weather map? They connect areas that have the same air
pressure.
2. How can an isobar line help scientist figure out where high or low pressure systems are
located? Scientists can plot the air pressure of different areas and connect all the places with
the same air pressure with an isobar.
3. How does air pressure affect wind speed? The larger the difference in air pressure, the faster
the wind will move.
4. In High pressure systems air flows outward from the high pressure center of the system.
5. Air leaving a high pressure system rotates clockwise.
6. In Low pressure systems air flows in toward the area of low pressure and rotates
counterclockwise.
7. High pressure air is cool and dry, high pressure systems usually bring dry, clear weather.
Clouds might be present, but generally little or no rain falls.
8. Low pressure systems is warm, humid air. Low pressure systems brings warm and stormy
weather. Storms and rain often follow a drop in air pressure.
9. When the barometer reading drop, suddenly, it is likely that precipitation will fall.
10. Occluded means “block or close off”
11. The properties of an air mass depends on the region in which it forms.
12. Air masses can be cold or warm and dry or humid. Air masses that form over water tend to be
humid. Air masses that form over land tend to be dry. Air masses that form in the tropics is
hot. Air masses that form near the poles, it is cold.
13. Cold front- cold air moves in under a warm air mass. Cold fronts bring brief, heavy storms.
After these storms, the skies become clear, and the weather is usually cooler and drier.
14. Warm front- warm air moves in over a cold air mass, warm fronts often bring light, steady rain
or snow. Afterward, the weather is usually warmer and more humid.
15. Occluded front- when a cold front catches up with a warm front. Cool air moves underneath
the warm front. This produces a wedge of warm air between two masses of cold air. The
formation of an occluded front often indicates that a storm will not last long.
16. Stationary front- is a boundary between two different air masses where neither one is strong
enough to replace the others.
17. What movers air masses? After an air mass forms, global winds may move it.
18. One type of global wind is the jet stream. The jet stream is a high-altitude wind caused by
large temperature differences between air masses. The jet stream can exceed speeds of
240km/h (150 mph).
19. Over North America, the jet stream blows from the west to east. Almost all weather fronts in
North America move from west to east.
20. Fronts help you predict future weather. Weather is typically similar to yesterday’s weather
further west.
21. 4 types of fronts: warm fronts, cold fronts, occluded fronts, stationary fronts
22. Symbols on weather maps represent different variables.
23. Cold fronts are shown as a blue line with blue triangles. The triangles point in the direction
the front is moving.
24. Warm fronts are shown with a red line of half circles that point in the direction the front is
moving.
25. Meteorologists are scientists who study Earth’s atmosphere and weather. They track
variables that affect weather to make forecasts, or predictions, about what weather will
occur.
26. Weather predictions may not always be accurate. Meteorologists constantly measure
variables because sudden changes in one variable can change the weather.