Global Wind Patterns

What is Wind?

• Wind is the movement of air from an area of higher pressure to an area of lower pressure. Warmer air expands, becoming less dense than colder air. This causes air pressure to be generally lower where air is heated.

The Coriolis Effect

http www.youtube.com/watch?v=mcPs_OdQOYU

• Coriolis Effect – Rotation of the Earth causes moving air and water to change directions• Northern Hemisphere winds curve to the right• Southern Hemisphere winds curve to the left.

• The Coriolis Effect - The tendency for any moving body on or above the earth's surface, such as an air or water current, to drift sideways from its course because of the earth's rotation. This affects Earth’s winds and water movement. Air moves to the right in the Northern Hemisphere. In the Southern Hemisphere, they move to the left.

Warm Moist Air Rises

Warm Moist Air Rises

Cool Dry Air Sinks

Cool Dry Air Sinks

Warm Moist Air Rises

Cool Dry Air Sinks

Cool Dry Air Sinks

Cold Moist Air Rises

Cold Moist Air Rises

Warm Moist Air Rises

Cool Dry Air Sinks

Cool Dry Air Sinks

Cold Moist Air Rises

Cold Moist Air Rises

Very Cold Air Sinks

Very Cold Air Sinks

Warm Moist Air Rises

Cool Dry Air Sinks

Cool Dry Air Sinks

Cold Moist Air Rises

Cold Moist Air Rises

Very Cold Air Sinks

Very Cold Air Sinks

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Wind Moves from HIGH to LOW

Objects are deflected to the

RIGHT in the Northern Hemisphere

Global Winds• Global Winds - Wind gets its name from the

direction it is blowing FROM!

Winds in the Upper Troposphere

• The jet stream is a current of fast moving air found in the upper levels of the troposphere.

Jet Stream• Discovered in 1940’s• Can be found in the upper troposphere• Strong high speed and high pressure• Moves west to east across the US, movingstorms

• The polar jet stream forms at the boundary of cold, dry polar air to the north and warmer, more moist tropical air to the south.

What brings certain weather phenomenon?

El Nino La Nina• occurs when the surface

temperature rises above the normal water temperature in the Equatorial Pacific Ocean creating more humidity in the atmosphere

• Known to increase number of hurricanes

• Occur more frequently (every 3-7 years)

occurs when the surface temperature falls below the normal water temperature in the Equatorial Pacific Ocean creating a more dry atmosphere

Known to create drought conditions

GLOBAL FORCES• The following global forces can affect the

formation of surface currents.

Equator

Earth’s Rotation

Continental DeflectionGlobal Forces

Continental Deflection

Since the Earth’s surface is not fully covered by water, currents cannot move freely around the world. So when surface currents meet continents, they deflect, or change direction.

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Predict what will happen with each labeled area.

Equator

Earth’s Rotation

Continental Deflection

Coriolis Effect

Global Forces

Coriolis Effect

The Earth’s rotation causes surface currents to move in curved paths rather than in a straight line.

North Pole

Earth’s Rotation

Equator

Earth’s Rotation

Continental Deflection

Coriolis Effect

Global ForcesGlobal Winds

Global WindsGlobal winds are affected by their latitude and the Coriolis Effect. In the tropics winds blow from the east to the west. In more temperate areas, the winds blow from the west to the east. Near the poles the winds blow from the east to the west.

Tradewinds

Tradewinds

Westerlies

Westerlies

Polar Easterlies

Polar Easterlies

Equator

Earth’s Rotation

Continental Deflection

Coriolis Effect

Global Forces TransparencyGlobal Winds

Deep Ocean Currents

Deep Ocean Currents

• Deep cold currents move water toward the equator.

• Cold water rises to replace warm water leaving.

• Warm water travels near the surface toward polar regions.

• Warm water replaces cold water.

Equator

Earth’s Rotation

Continental DeflectionSince the Earth’s surface is not fully covered by water, currents cannot move freely around the world. So when surface currents meet continents, they deflect, or changedirection.

Coriolis EffectThe Earth’s rotation causes surface currents to move in curved paths rather than in a straight line.

Global Forces Global WindsGlobal winds are affected by their latitude and the Coriolis Effect. In the tropics winds blow from the east to the west. In more temperate areas, the winds blow from the west to the east. Near the poles the winds blow from the east to the west.

Deep Ocean CurrentsDeep cold currents move water toward the equator.Cold water rises to replace warm water leaving.Warm water travels near the surface toward polar regions.Warm water replaces cold water.