1. Global Weather Patterns

2. Global Weather Patterns
Weather forecasters must look at global weather patterns to more accurately predict local weather.
For example, a cold air mass coming towards North Carolina might have come from the North Pole.
The ocean water flowing past our state right now could have come from the equator.

3. Currents
Currents in the atmosphere and oceans transfer heat around the world and cause weather.
A current is a flow of air or water in a certain direction.
In the air, these currents are called global winds.

4. Global Winds
The sun’s energy heats the Earth through radiation. The Earth is not heated evenly.
The equator gets the most direct sunlight with the poles getting the least. This causes different temperatures.
The uneven heating of the Earth causes air movement, or wind.

5. Global Winds
The Earth’s rotation causes the paths of global winds to curve. In the northern hemisphere, winds traveling north curve to the east. Winds traveling south curve toward the west.
The paths of the winds help meteorologists predict the movement of air masses.

6. Jet Stream
The jet stream is an air current in the upper atmosphere that flows from west to east like a river of air.
The jet stream greatly affects the weather in the U.S. The jet stream has cold air on the top and warmer air on the bottom.
The jet stream dips, bends, and changes position, causing changes in weather.

7. Jet Stream
When the polar jet stream dips south, it lets cold air from Canada flow down into the United States. When the subtropical jet stream bends north, it lets warm air flow up from the south.
Meteorologists use jet streams to predict the path of storms.
Click the link to review global winds:

8. Ocean Currents
Ocean water is always moving and flowing as currents. Ocean currents flow in a certain direction.
Winds can cause currents near the water’s surface. Other currents flow deep below the surface. The map below shows some of the main ocean currents.

9. Ocean Currents
Some currents are warm and others are cool. Warm currents flow away from the equator and cool currents flow away from the poles.
Ocean currents affect weather patterns by sending cool or warm water along coastlines, affecting the temperature in the area.
Click the link below to learn more about ocean currents:

10. The Gulf Stream
The gulf stream is a warm ocean current in the Atlantic Ocean. It flows northwest along the eastern coast of the United States.
The gulf stream moves warm waters out across the Atlantic Ocean and then toward the north.
This current helps keeps weather mild in winter along the east coast of the U.S. and the western coast of Europe.

11. The Gulf Stream

12. El Niño and La Niña
Changes in ocean temperatures can affect weather patterns for a long period of time.
Every few years, such a change occurs in the Pacific Ocean in the form of El Niño or La Niña.
El Niño = unusual warming of surface water in eastern Pacific near the equator
La Niña = unusual cooling or the water in the same area