Types of Wind: Classification and Explanation

• As the sun heats the surface of the earth, the atmosphere also warms.
• However, our hills and oceans cause unequal heating, and the poles receive less solar energy than the equator. 
• The difference in solar input, together with the rotation of the earth, produces global atmospheric circulation patterns and the most common surface winds.
• From the equator, hot air rises, moves north to the poles, sinks, and flows south to replace the air at the equator. 
• Winds and air currents are both caused by air movement, but they are not the same thing.
• Winds happen when air flows horizontally in response to pressure, whereas air currents occur when air moves vertically or almost vertically.
• There are three types of winds: prevailing, seasonal, and local.

Key Terms: Wind, Types of wind, Atmosphere, Heat, Temperature, Poles, Atmospheric pressure, Temperature difference, Anemometer, Wind vane, Planetary Wind, Periodic Wind, Local Wind

What is Wind?

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Moving air is called wind. Winds are caused due to uneven heating of the atmosphere. Since air is a mixture of gases, wind is a flow of gases on a large scale.

• Winds are mainly caused by heating differences between different parts of the world and the movement of the earth.
• The heating of the surface of the earth is uneven because land heats faster than the ocean.
• As a result, the air above the heated surface rises, creating a low atmospheric pressure.
• This low-pressure area is filled with cold air that travels from the high-pressure area.
• Winds develop as a result of horizontal air movement.
• The winds balanced the unequal distribution of pressure in the atmosphere.
• Anemometers are used to measure wind speed.
• A Wind vane is a device used to detect wind direction.

Wind

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Classification of Wind

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Based on the periodicity of occurrence and location of occurrence, winds are broadly classified into three categories:

• Primary Wind or Planetary Wind
• Secondary Wind or Periodic Wind
• Tertiary Wind or Local Wind

Classification of Wind

Primary Wind or Planetary Wind

Primary winds blow over continents and oceans. Primary winds are also called Prevailing Wind and Permanent winds.

• The two most significant winds for the climate and human activities are trade winds and westerly winds.
• Examples are Trade Winds, Westerlies, and polar Easterlies.

Secondary Wind or Periodic Wind

Secondary Winds are confined to a particular season and to a particular area.

• They usually change their direction with the season.
• Secondary Winds are also known as Seasonal winds.
• An example of seasonal wind is the Monsoonal Wind system in the Indian Ocean.

Tertiary Wind or Local Wind

Tertiary Wind only blows during a particular period of the day or year in a small area.

• These winds blow because of the difference in the temperature and the air pressure of a specific location.
• Examples are Blizzards, Chinooks, Santa Ana, Mistral, and Simoon.

Different Types of Wind

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The following are the different types of wind

The Westerlies

The westerlies are also known as anti-trades, prevailing westerlies, and are the prevailing winds from the west toward the east in the middle latitudes between 30- and 60-degree latitude often bringing depressions and anticyclones.

Polar Easterlies

The polar easterlies are the dry, cold prevailing winds that blow from the high-pressure areas of the polar highs at the north and south poles towards low-pressure areas within the Westerlies at high altitudes. Since the winds originate in the east, they are then known as easterlies.

Trade Winds

The trade winds are winds that reliably blow east to west just north and south of the equator. The wind helps ships travel west, and they can also steer storms such as hurricanes. The trade winds are air currents closer to Earth’s surface that blow from east to west near the equator.

Monsoon Winds

The seasonal wind of the Indian Ocean and Southern Asia from the Northeast in winter (in India and nearby islands) is the season during which the southwest monsoon blows, commonly marked by heavy rains, any wind that changes directions with seasons.

Land Breeze and Sea Breeze

During the daytime, the air above the land gets heated faster than water. Hot air above the land rises creating a low-pressure area and air from the sea moves into the area. This a called sea breeze.

During the night, both the land and sea start cooling. But the cooling of the sea takes place at a slower rate than that of the land. Thus, a low-pressure area is created in the sea. The air then moves from the land to the sea. This is called land breeze.

Mountain and Valley Breeze

Local Winds

Local winds are winds that blow over a limited area. Local winds blow between small low- and high-pressure systems. They are influenced by the local geography. Nearness to an ocean, lake, or mountain range can affect local winds.

How is Wind Measured?

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Anemometers

Wind speed is measured with an anemometer. Most anemometers have four horizontal shafts arranged like the spokes of a wheel.

• The end of each shaft is cup-shaped.
• The wind pushes the concave side of the cup more than the convex side, so the anemometer spins in the wind.
• The faster the anemometer is spinning, the stronger the wind.

Wind vanes

Wind direction is measured with a wind vane. One end of the vane has a small, heavy object, and the other end has a flat object with a large area.

• The wind pushes the flat object more than the small, heavy objects, so the vane swings around to be parallel to the wind.
• You can estimate the wind direction by yourself just by using your face as a "sensor."
• Face into the wind, and then record the direction you are facing, relative to the north.

Things to Remember

• The movement of air is caused by pressure differences driven by changes in temperature.
• The winds balanced the unequal distribution of pressure in the atmosphere.
• Winds are broadly classified into three categories: Primary or Planetary Wind, Secondary or Periodic Wind, and Tertiary or Local Wind.
• Primary winds blow over continents and oceans.
• Secondary Winds are confined to a particular season and to a particular area.
• Tertiary Wind only blows during a particular period of the day or year in a small area.
• An anemometer is a device used to measure wind speed.

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