What is Wind?
The flow of gasses or movement of bulk air on the surface of Earth is Wind. Various attributes of the wind include the types of forces that cause them, the regions in which they occur, and their effect, wind speed and spatial scale. Wind also occurs in outer space called the solar wind. It involves the movement of charged particles and gasses from the sun through space. Wind speed, the density of gas that’s causing the wind, wind energy are all different aspects of it. It has its strength and direction of flowing.
Wind Currents
An increase in wind speed accompanies the reduction in air pressure, which is a pressure exerted by the air around us. This is also followed by the movement of air from the high-pressure region to the low-pressure region. So, wind currents are air currents of considerable force moving mostly in the horizontal direction from an area of high pressure to areas of low pressure. Air becomes light on heating, because it expands, and to occupy more space due to expansion it rises up. Warm air is lighter than cool air which can be illustrated by the fact that smoke always rises.
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Storm
Storms are generated when a center of low pressure develops with the system of high pressure surrounding it. It is marked by high wind moving at great wind speed. The regions that lie close to the equator receive more heat from the sun. Due to this, the warm air rises. This suggests that the warm air from the equator moves in to take its place. On the other hand, the air at the poles is colder than the air at the equator. Thus, as the warmer air rises, the cooler air from the poles race in. Consequently, wind currents move from poles to warmer latitudes due to the uneven heating of the earth’s surface.
There are many types of storms like Dust storms, in which the visibility gets badly impacted as the wind picks up large quantities of sand, soil. Hailstorm occurs due to the precipitation of chunks of ice. Ice storm, that is one of the most dangerous forms of winter storms. It occurs when surface temperatures are below freezing, but a thick layer of above-freezing air remains aloft, rain can fall into the freezing layer and freeze upon impact into a glaze of ice. The snowstorm is characterized by heavy snowfall. Thunderstorms, Cyclones, and so on.
Thunderstorm
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A thunderstorm is characterized by the presence of lightning along with thunder. Generally, it develops in hot and humid regions like India. High temperature creates strong and upward currents. These currents carry moisture, that is, water vapor along with them to higher altitudes. This is followed by the process of condensation and rain again. These pressure variations are accompanied by thunder, lightning, and strong winds.
Conversion of Thunderstorm to Cyclone
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When moisture changes to the liquid form of water, that is, water drops, it leads to the release of heat to the atmosphere. Thus, the heat released in this way warms the surrounding air and gives rise to a pressure drop. All of these consequences lead the air to rush in towards the center of the storm. This cycle creates large low-pressure systems with strong high-speed winds swirling around them. This is how the cyclone forms.
Cyclone
A cyclone is a huge mass of rotating air that has a speed of nearly 1015 km high in the air.
The center of the cyclone is calm and is known as the eye of the storm.
The eye of the storm mostly has a diameter ranging from 10 to 30 km.
Around the eye of the storm, lies a region of clouds of about 150 km. The speed of wind inside it is about 150-250 km/hr.
The speed of the wind decreases as it moves away from the eye of the storm.
Cyclones are also called Hurricanes or Typhoons.
Generation of Wind Currents as a Result of Unequal Heating of the Earth
There are two situations in which winds on Earth generate:
North-south winds are caused by uneven heating between the equator and the poles.
We know that the Earth is divided into circular lines called latitudes, which indicate a location's north-south position on the globe.
In addition, the equator is a latitude that is perpendicular to the Earth's rotational axis.
On Earth, the locations closest to the equator receive the most sunlight.
As a result, the air in these areas is often warm. As a result, warm air climbs above, while cold air from latitudes near the equator goes in that direction.
Similarly, chilly winds from the North and South poles travel towards the equator and neighboring latitudes, and wind circulation occurs on Earth.
Uneven heating of land and water results in monsoon winds, which deliver rain to the earth.
During the summer, the land near the equator warms and its temperature remains higher than that of the oceans.
As a result, what is above the land rises, and cold air from the oceans travels towards it. These are known as monsoon winds.
Because these winds originate in the ocean, they take water with them. Similarly, during the winter season, winds migrate from the land to the oceans.
FAQs on Wind, Storm and Cyclones
1. What is the difference between wind, a storm, and a cyclone?
The primary difference lies in their intensity and scale. Wind is simply the movement of air from a high-pressure area to a low-pressure area. A storm is a more intense weather disturbance with very strong winds, often accompanied by rain, thunder, and lightning. A cyclone is a very large, powerful, and rotating storm system that forms over warm ocean waters. It has a low-pressure centre known as the 'eye'.
2. What are the main conditions required for a thunderstorm to develop?
Thunderstorms form in hot and humid tropical areas. The key conditions required for their development are:
Moisture: Sufficient water vapour in the air to form clouds.
Rising Warm Air: As the sun heats the ground, the air above it becomes warm and rises rapidly.
Updraft: A continuous upward movement of this warm, moist air, which then cools, condenses, and forms tall cumulonimbus clouds, leading to lightning, thunder, and rain.
3. How does air pressure influence the generation of wind?
Air pressure is a fundamental factor in creating wind. The sun's heat causes air to expand and rise, creating an area of low air pressure. In contrast, cooler, denser air sinks, creating an area of high air pressure. Nature always seeks balance, so air naturally moves from regions of high pressure to regions of low pressure. This movement of air is what we experience as wind.
4. Why can high-speed winds sometimes blow away the roofs of houses?
This happens due to a principle where high-speed winds are accompanied by reduced air pressure. When strong winds blow over a sloped roof, it creates a low-pressure zone above it. The air pressure inside the house, which remains higher, pushes upwards on the roof. If this upward force is strong enough, it can lift the roof and blow it away. This is why houses in windy areas often have ventilators to help equalise the pressure.
5. What is a tornado and how does it form?
A tornado is a violently rotating, dark, funnel-shaped cloud that reaches from the sky to the ground. Tornadoes typically form from severe thunderstorms when there are significant differences in wind speed and direction at different altitudes. This creates a rotating column of air that can be tilted vertically, forming the destructive funnel. Wind speeds inside a tornado can be extremely high, reaching over 300 km/h.
6. How does the uneven heating of the Earth cause global wind currents?
The Earth is heated unevenly by the sun. Regions near the equator receive more direct sunlight, causing the air to become very warm and rise, which creates a permanent low-pressure belt. At the poles, the air is much colder and denser, causing it to sink and create high-pressure zones. To balance this pressure difference, cooler air from the poles flows towards the equator, and warm air from the equator flows towards the poles, setting up large-scale global wind currents.
7. What are the essential safety measures to follow during a cyclone warning?
If a cyclone is forecast for your area, it is crucial to take the following precautions:
Pay close attention to warnings issued by the meteorological department on TV, radio, or online.
Move to a designated cyclone shelter or a safer concrete building. Stay away from coastal areas.
Prepare an emergency kit with essentials like drinking water, non-perishable food, a first-aid kit, and a flashlight.
Keep emergency contact numbers for police, fire brigade, and medical services readily available.
Do not venture outdoors, especially near the sea, and avoid driving.
8. What is the 'eye of a cyclone' and why is this region calm?
The eye of the cyclone is the calm, low-pressure centre of a mature and powerful cyclone. This area is calm because the air in the eye is sinking, not rising. Sinking air prevents cloud formation, resulting in clear skies and very light winds. This calm centre is surrounded by the 'eyewall', which is the most dangerous part of the cyclone with the strongest winds and heaviest rain.
9. How do monsoon winds bring seasonal rain to India?
Monsoon winds are a large-scale example of wind caused by uneven heating. During the summer, the landmass of India heats up much faster than the surrounding Indian Ocean. This creates a strong low-pressure area over the land. To fill this gap, moisture-laden winds from the high-pressure zone over the ocean blow towards the land. As these winds travel over the land, they rise, cool, and condense, resulting in widespread seasonal rainfall known as the monsoon.
10. Compare the key differences between a thunderstorm and a cyclone.
While both are storms, thunderstorms and cyclones differ significantly:
Scale: A thunderstorm is a relatively small-scale event, often just a few kilometres across. A cyclone is a massive-scale system that can span hundreds of kilometres.
Formation: Thunderstorms can form over land or sea. Cyclones only form over warm ocean waters (typically above 27°C).
Structure: A cyclone is a large, organised rotating system with a distinct low-pressure eye. A thunderstorm does not have this large-scale rotational structure.
Duration: A thunderstorm is usually short-lived, lasting from 30 minutes to a few hours. A cyclone can persist for several days or even weeks.
