Weather Systems

Coriolis Effect Imagine how the atmosphere acts as the Earth rotates on its axis. It is NOT attached to Earth’s surface! Coriolis effect Coriolis Effect

Coriolis effect The Coriolis effect is the apparent deflection of a body in motion with respect to the Earth, as seen by an observer on Earth. It is caused by the rotation of the earth

Coriolis Effect NASA – Coriolis Effect on Astronauts Plane travel – Coriolis Effect on Air Travel

Global Wind Systems Three basic zones, or wind systems in each hemisphere Remember that winds are named for the direction that they blow FROM, not TO

Trade Winds Trade Wind air moves toward the equator Warm, steady, continuous breezes Appear to be curving to the west. Why?

Doldrums The doldrums are an area of calm weather The trade winds meet near the equator Produce upward winds as they are heated, so there are no steady surface winds. 

Prevailing Westerlies The prevailing westerlies are between 30 and 60 latitude Winds are named from the direction that they blow from. In Northern Hemisphere - responsible for movement of weather west to east across US and Canada

Polar Easterlies Polar easterlies are found between 60 latitude and the poles Consist of cold air

Jet Streams Jet streams are narrow bands of fast, high-altitude westerly winds Most significant - polar jet stream

4 Types of weather fronts: Cold Front Warm Front Stationary Front Occluded Front

Cold front The direction that the teeth point indicate the direction the front is moving.

Cold Front

What is happening? Fast moving cold air mass slow moving warm air mass Cold air slides under the lighter warmer air. The weatherman says… Clouds, showers, and sometimes thunderstorms associated with cold fronts

Warm Front

Warm Front

Faster moving warm air mass takes over the slowly moving cold air mass Warm air moves over the cold air. And the weather man says… Associated with cloudiness and precipitation

Stationary Front

Stationary Front

Cold air mass and warm air mass meet. Neither air mass has enough force to move the other air mass out of the way.

Occluded front

Occluded Front

Warm air mass is caught between two cooler air masses Cold air masses move underneath the warm air mass and push it upward. The weatherman says… Precipitation is common on both sides of an occluded front.

Which types of fronts can you find?

High vs Low Pressure Systems Rising and sinking air results in rotation High-pressure system: Air sinks and spreads away from the center Rotates clockwise direction in N hemisphere (counterclockwise in S hemisphere) Low-pressure system: Air rises and moves counterclockwise N hemisphere (clockwise S hemisphere)

High VS Low Pressure Systems High pressure systems - fair weather Low pressure systems - clouds and precipitation

map showing isobars, lines of equal pressure.