Global Wind Patterns

​LESSON:

Local Winds and Global,
Jet Streams, and Coriolis Effect

I CAN STATEMENT

I can explain the influence of convection,
global winds, and the jet stream on weather
and climatic conditions.

LOCAL WINDS

Local winds form due to differences in air pressure caused by the uneven heating of the Earth's surface. Here's how the process works:

UNEVEN HEATING OF LAND AND WATER:
Land heats up and cools down more quickly than water. During the day, the land gets warmer than
the nearby water bodies (like lakes or oceans). At night, the land cools down faster than the water.
DIFFERENCE IN AIR PRESSURE:
- Warm air is less dense and rises, creating an area of low pressure.
- Cool air is denser and sinks, creating an area of high pressure.
AIR MOVEMENT FROM HIGH TO LOW PRESSURE:
Air always moves from areas of high pressure to areas of low pressure. This movement of air
creates wind.

Multiple Choice

What causes local winds to form?

• Changes in humidity

• The Earth's gravitational pull

• Differences in air pressure due to uneven heating

• The Earth's rotation

Multiple Choice

What happens to warm air as it rises?

• It creates an area of high pressure

• It creates an area of low pressure

• It becomes cooler and denser

• It forms clouds

Multiple Choice

What does cool air do because it is denser than warm air?

• It sinks and creates high pressure

• It rises and creates low pressure

• It expands and creates wind

• It absorbs heat from the land

Multiple Choice

How does air move in relation to pressure differences?

• From warm areas to cool areas

• From areas of low pressure to areas of high pressure

• From the ocean to the land

• From areas of high pressure to areas of low pressure

Multiple Choice

How does air move in relation to pressure differences?

• From warm areas to cool areas

• From areas of low pressure to areas of high pressure

• From the ocean to the land

• From areas of high pressure to areas of low pressure

TYPES OF LOCAL WINDS:

​At night, the land cools down faster than the water. The air over the water remains warmer, creating low pressure. Cooler air from the land (which has higher pressure) moves toward the water, creating a land breeze.

During the day, the land heats up faster than the water. Warm air over the land rises, creating low pressure. Cooler air from the ocean (which has higher pressure) moves in to replace the rising warm air, forming a sea breeze.​

Multiple Choice

During a land breeze, where does the cool air come from?

• From the ocean

• From the clouds

• From the land

• From the sun

Multiple Choice

What causes a land breeze at night?

• The land cools down faster than the water

• The water cools down faster than the land

• The air over the land becomes warmer than the air over the water

• The land heats up faster than the water

Multiple Choice

What happens during a sea breeze?

• Cool air from the land moves toward the ocean

• Warm air from the ocean moves toward the land

• Cool air from the ocean moves toward the land

• Warm air from the land moves toward the ocean

Multiple Choice

Why does a sea breeze occur during the day?

• The ocean heats up faster than the land

• The land heats up faster than the water

• The ocean cools down faster than the land

• The air over the land stays cooler than the air over the ocean

Global Wind Patterns

Trade Winds flow through the tropics.  They steer tropical storms in the ocean.

•Westerlies (originate from the west)move air masses and fronts.
Polar winds or Easterlies( originate from the east) They are cold and dry winds that blow around the north and south poles

Explore : Stations rotations

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Labelling

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westerlies

horse shoe latitude

polar easterlies

horse shoe latitude

trade winds

westerlies

trade winds

doldrums

doldrums

polar easterlies

CORIOLIS EFFECT

The Coriolis Effect is the apparent deflection of moving objects (like air masses or ocean currents) caused by the rotation of the Earth. It influences wind patterns and ocean currents.

How the Coriolis Effect Works:

• Earth's Rotation: The Earth rotates on its axis from west to east. This rotation affects how objects move across the surface.

• Deflection Direction:

  • In the Northern Hemisphere, moving objects (including air) are deflected to the right of their direction of travel.

  • In the Southern Hemisphere, moving objects are deflected to the left of their direction of travel.

• Impact of Latitude:

  • The Coriolis Effect is strongest at the poles and weakest at the equator. At the equator, there is little to no deflection because the rotational speed is highest there.

  • As you move towards the poles, the Coriolis Effect increases, leading to more significant deflection.

Importance of Coriolis Effect

​The Coriolis Effect is crucial for understanding weather systems and climate. It helps explain why cyclones rotate in different directions in the two hemispheres: hurricanes in the Northern Hemisphere rotate counterclockwise, while in the Southern Hemisphere, they rotate clockwise.

Multiple Choice

What causes the Coriolis Effect?

• The gravitational pull of the moon

• The Earth's rotation

• The uneven heating of the Earth's surface

• Changes in atmospheric pressure

Multiple Choice

Which of the following best describes the movement of air due to the Coriolis Effect?

• Air moves in a straight line from high to low pressure

• Air remains stationary

• Air moves only vertically

• Air is deflected sideways as it moves

Multiple Choice

The Coriolis Effect is crucial for understanding which of the following phenomena?

• The size of ocean waves

• The melting of polar ice caps

• The rotation of hurricanes
  

• The temperature of ocean currents

Multiple Choice

In which direction are moving objects deflected in the Northern Hemisphere due to the Coriolis Effect?

• To the right

• To the left
  

• Straight ahead

• Circular or rotating

WHAT IS A JET STREAM?

​A JET STREAM is a fast, narrow, and powerful air current that flows high in the atmosphere, typically at altitudes of around 6 to 12 miles (10 to 20 kilometers) above the Earth's surface. Jet streams are found in the upper levels of the troposphere and lower stratosphere and usually form at the boundaries between large air masses of different temperatures, such as the polar regions and warmer areas closer to the equator.

KEY FEATURES OF JET STREAMS

• High Speed: Jet streams can travel at speeds of 100 to 200 miles per hour (160 to 320 kilometers per hour) or more.

• Narrow Bands: They are relatively narrow, often a few hundred miles wide, but can stretch for thousands of miles around the Earth.

• Westerly Winds: In most cases, jet streams flow from west to east due to the rotation of the Earth, but they can shift and meander north and south, which affects weather patterns.

TWO MAIN TYPES OF JET STREAMS?

1. POLAR JET STREAM: Found closer to
the poles, this jet stream separates cold polar air from warmer air to the
south. It tends to have stronger winds
and plays a key role in weather systems
in mid-latitude regions.

2. SUBTROPICAL JET STREAM: Located
closer to the equator, this jet stream
forms near the boundary between
tropical and subtropical air masses.

Multiple Choice

What causes jet streams to form?

• The Earth's gravitational pull

• Differences in air pressure near the ocean

• The boundaries between large air masses of different temperatures

• Changes in humidity levels and convection currents

Multiple Choice

In which direction do jet streams typically flow?

• North to South

• South to North

• East to West

• West to East

Multiple Choice

Where are jet streams typically located in the atmosphere?

• In the lower troposphere and the surface of the Earth

• In the upper levels of the troposphere and lower stratosphere

• Near the Earth's surface

• In between the stratosphere and mesosphere

Multiple Choice

How can jet streams affect air travel?

• Planes flying with a jet stream can move faster

• Jet streams always slow planes down

• Jet streams cause planes to rise in altitude

• Jet streams prevent planes from flying at high altitudes