Answer:
Jet streams, warmer air
Step-by-step explanation:
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Jet Streams
About 10 km above Earth’s surface are bands of high-speed winds called jet streams.
Meteorologists use the location of some of the jet streams as an aid in weather forecasting.
Jet streams generally blow west to east.
Jet streams form at the boundary of adjacent air masses with significant differences in temperature (polar region vs. Equator).
Jet streams move weather systems across the U.S.
Jet streams have a meandering shape.
warm air is flowing on the bottom and cold air on the top