Wind can be simply defined as moving air. When air moves from one place to another, we call it the moving air wind. In this article, we discuss the types of wind along with some examples.
We cannot see the movement, but we can feel it as it passes through us. We can see the windmill rotating due to wind and also can hear the wind pass through in a storm or cyclone. A few centuries ago winds were a major source of energy for transport and nowadays it is a power source in terms of mechanical energy for the generation of electricity in windmills and also for recreation purposes like flying kites. The wind is a renewable source of energy and is very vital for sustainable development.
Types of Wind
On planet Earth, wind can be classified into 5 major categories. The classification is based on the periodicity of occurrence and location of occurrence.
- Planetary winds
- Trade winds
- Westerly winds
- Periodic winds – Monsoon breeze, Land breeze, Sea breeze, Mountain and valley breeze
- Local winds
Planetary Winds
The air pressure is not the same across the planet Earth. The air pressure is different in different latitudes. This difference in air pressure gives rise to air movement across the planet hence it is called “planetary” or “prevailing winds”.
This type of wind is important for migratory birds. As birds can easily migrate under tailwinds, they wait on the ground during headwinds. But, sadly due to global warming, the wind patterns are being affected by changes in atmospheric pressure because of the temperature change.
Trade Winds
Trade winds also called “tropical easterlies,” are steady winds blowing from subtropical high-pressure areas towards the low-pressure equatorial belt.
These winds blew from north to south in the Northern Hemisphere and from south to north in the Southern Hemisphere. But, as they blow they get deflected to the right in the Northern Hemisphere and to the left in the Southern Hemisphere due to the Carioles effect and Ferrell’s law. Because of this deflection, they are called northeastern trades in the Northern Hemisphere and southeastern trades in the Southern Hemisphere.
Why trade winds are called so?
This wind was instrumental for ships crossing across the Atlantic between the 14th -18th centuries. So, the trade ships would plan their routes accordingly across Africa, America, and Europe. The route is planned in the direction of the wind to assist the sailing, and often the routes would be spanning across hemispheres and continents to achieve this.
The Westerly’s
The westerly’s winds blow from subtropical high-pressure belts towards sub-polar low-pressure belts. These winds blow above and below the trade winds in the northern and southern hemispheres respectively.
Since these winds develop at a latitude between 40° and 65°S they are commonly referred to as are known as Roaring Forties, Furious Fifties, and Shrieking Sixties.
Why westerly’s are called so?
These winds blow from the west towards the east between the subtropical and sub-polar regions and hence the name.
Periodic Winds
The name periodic wind itself suggests that these winds change direction periodically according to seasonal changes. They are not constant as other winds we discussed and change direction with respect to the prevailing atmospheric conditions.
Types of periodic winds
Monsoon Winds
Monsoon winds are seasonal. It generally occurs in low-latitude climates like the Indian sub-continent and changes direction between winter and summer. In the Indian sub-continent, the temperature difference between the Indian Ocean/bay of Bengal/Arabian sea and the low-temperature Himalayas forms the basis of the winds.
Land Breeze
At night, the land cools quicker than the sea due to the rapid radiation effect. This results in high-pressure regions over land and low pressure over the sea. This pressure difference causes the wind from the land to the sea. This type of wind is dry and warm.
Sea Breeze
In the daytime, the land is hotter than the sea. The hot air rises up and creates a low air pressure area over the land. Since the sea is cool a high-pressure region is created over the sea. The wind flows from sea to land called a sea breeze. This type of wind carries some moisture along with it and is cool.
Mountain and Valley Breezes
Mountain and valley winds work on the same principle as land and sea breezes. During the daytime the slopes of mountains are hot (low pressure) and air from the valley (high pressure) flows up the slopes due to this pressure difference. This is called “Valley Breeze”.
In the evening the direction of the wind is reversed where cold air from the mountain flows to the valley. This is called “mountain breeze”.
Local winds
Local winds as the name suggest flowing through short distances. These winds are affected by mountains, vegetation, water bodies, and human activities. These winds are not constant and change very often. Such wind forecasts are generally reported on radios and television stations as they can change within hours.
What is the negative impact of winds?
- The force of the wind can be very powerful. When winds become strong, they lead to tremendous destruction of life and property in the form of some cyclones and storms.
- Winds can also aggravate forest fires and other natural disasters like landslides and blizzards.
- Some types of wind change direction suddenly based on some uncontrollable factors. Since there is a temperature change associated with the winds they can affect our crops.
What is the positive impact of winds?
- Winds were used for navigating ships.
- Migratory birds use the wind direction for the migration.
- The wind is a source of renewable energy, which can be tapped using windmills.
- The cool breeze of the wind refreshes us.
Why is wind caused?
- The Earth is not a perfect sphere, it is an ellipsoid. Since the earth is an ellipsoid and is tilted, the equator receives the maximum amount of sunlight. The polar regions receive a relatively lesser amount of sunlight. And this amount changes depending on the seasons. This difference in temperature causes a pressure difference across latitudes. Most of the wind types are caused due to this factor.
- The local winds depend on local activities like volcanic eruptions, barriers to flow, etc.
- The temperature difference between the land and sea in coastlines causes a pressure difference that gives rise to winds. This is also seen in the case of mountains and valleys.
