Wind

Earth’s atmosphere resembles a blanket of gases that wraps around the globe. It is 400 miles high and consists of 78% nitrogen and 21% oxygen, as well as argon, carbon dioxide, hydrogen, and many other gaseous elements. This mixture of gases is what we call Air.

There are five layers of the atmosphere; they may look like a big layered cake but are actually our windows to the universe!

The troposphere is the layer of Earth's atmosphere that is the closest to us. Here is where all weather (wind, rain, snow, thunder and lightning, etc.) takes place. This is also where jet planes fly.

The stratosphere is the second portion of Earth's atmosphere as you go upward. This layer is rich in ozone, an uncommon type of oxygen that heats up because it receives energy from the Sun.

The mesosphere begins at 31 miles and reaches up to 53 miles in the sky. This layer protects the Earth by burning up most meteors and asteroids long before they hit the ground.

The thermosphere layer extends from the mesosphere to the outermost region of the atmosphere. “Thermo” means heat because this portion is really hot! Its gas can reach up to 4,530 °F. 

The outermost region of a planet's atmosphere. It is the last layer where there is still some gravity.

Wind is the movement of large amounts of air. Cold air is more dense and will always fall due to gravity. Conversely, warmer air rises. 

Air will always want to equalize in pressure, so higher pressure will push the air to flow to places with lower pressure. This movement of air is wind.

Hot air rises and cool air sinks. This brings about spatial differences in atmospheric pressure, caused by uneven heating.

Cold air is dense, being heavier causes it to sink towards the ground due to gravity.

The movement of air from high pressure to low pressure is wind.

The direction of wind’s origin. If it comes from the south, the wind is southerly, and if it originates from the east, then the wind is easterly, and so on. You can easily recognize wind direction by using a windsock or a weather vane.

Warm air creates less pressure and is less dense, so it rises up.

In order to determine the different kinds of wind, we need to know their direction and their speed. For example, northerly winds blow from North to South, while southerly from South to North. We measure wind speed according to the Beaufort scale that determines 12 wind forces.

Force 0 is calm air, Force 4 means a moderate breeze, while the strongest is hurricane Force 12. Wind speed is measured using an anemometer, which rotates and records the speed.

This is absolutely still air. Smoke in this air would rise vertically, and water would be as clear as a mirror.

Gentle breeze develops a speed of about 8-12 miles per hour. You should be able to observe leaves and small twigs moved by it, and also paper cups if they are empty. 

Moderate winds have speeds of about 13-18 miles per hour. You can fly a kite and see the branches of trees moving.

When wind develops speeds of about 25-31 miles per hour, it causes high waves on the sea surface, and could even break off small branches from trees. It becomes difficult to use an umbrella.  

Gale winds have speeds of 39 miles per hour and up. They can be destructive and even rip off the roofs of houses. You can expect high tidal waves with them. It becomes difficult to progress on foot or drive a car. 

Globally, winds follow certain patterns based on Earth’s rotation, regional elevation, and climate. These global winds drive local winds and weather patterns. Local winds are formed because of changes in terrain, such as mountains, vegetation, and water bodies. 

Local winds cover very short distances and change very often. Weather forecasters talk about these kinds of wind every day. They can change in a matter of hours from mild to extreme. Good examples of local winds are sea breezes, land breezes, and valley breezes.

They go by different names, such as hurricane, cyclone, and typhoon, depending on where the storm occurs. Shaped like a spiral with a warm low-pressure center, known as the eye, they bring strong winds and thunderstorms that produce heavy rain. 

You can locate them on the Equator, forming a belt which extends to about 5° North and South. It is a low-pressure area caused by the constant sun heat. Doldrums are prevailingly calm. 

Also known as Tropical Easterlies, these winds are nearly constantly dominating most of the world's tropics and subtropics. They blow mainly from the northeast in the Northern Hemisphere, and from the southeast in the Southern Hemisphere.

This is the belt extending from 30° to 60° North and South of the Intertropical Convergence Zone (ITCZ). The Prevailing Westerlies are also known as anti-trades and tend towards the poles.

Land and sea breezes blow along coasts or large bodies of water, such as lakes and oceans. Water and land heat up differently. Although water needs more time to heat up, it can then maintain the warmth longer than land.

Cool gentle wind, moving from the sea towards the land. During the day the sun heats up the land quickly, so the cooler air over the water is attracted to the low pressure ground area.

Coastal breezes, blowing from land to sea, are caused by the difference in temperature that happens during the night. Land loses heat faster, while water retains warmth, so low pressure is created over the water, causing wind to blow from land to sea.

Elevation is a huge factor in the movement of air over land. Different elevations experience different levels of sun exposure, creating uneven heating and therefore, different levels of air pressure from peak to valley. This results in mountain or valley breezes.

When the sun is out, it causes the air near the top of the mountain to warm up.

During the day, the air above the mountain heats up more than the air at the foot of the mountain. It becomes less dense, creating low pressure at the top of the mountain. High pressure created from the cool air below drives a cool breeze to move up the mountain.

During nighttime (or, if it’s quite cold, during the entire day) the air that is at the foot of a mountain is warmer than the air that is at the top.

Mountain breeze forms as the high pressure area at the top makes the air blow downwards where the air is warmer. This event happens at night or during the colder months of the year. 

As warm, light equatorial air rises high in the atmosphere, the space left by it is filled by cold, dense air, coming from the poles. Earth is constantly rotating and as winds blow from the poles to the equator their path is deflected by the rotation of Earth. 

 If you throw a ball from the equator to another part of Earth, it doesn’t move in a straight line, but its path is curved. This phenomenon caused by the Earth’s rotation is called Coriolis Effect. 

Coriolis effect is caused by the rotation of the Earth.

With no rotation, an observer would see an object moving from the Pole to the target in a straight path.

With the earth’s rotation, an observer would see the object moving from the Pole to the target with a curved path.

Renewable energy is getting more and more attention worldwide, and wind has a leading role as the fastest growing source of electricity in the world. If you ask any expert, they would probably tell you wind is the cheapest form of power humans can exploit. 

Generating power with the help of wind is extremely gentle to the environment and leaves no dangerous waste products behind. Wind is abundant and can never be “out of supply.”

Windmills slow wind speed down. Wind flows over the fan, causing it to spin. The blades are connected to a shaft that turns a mill; they are traditionally used to grind grains.

Wind turbines convert the wind into mechanical power that can be harnessed in different ways. For example, producing electricity via generators, or simply pumping water. Using wind power is one of the cheapest renewable energy technologies.

Wind turbines are used for converting wind’s kinetic energy into electrical power. Large groups of wind turbines are called wind farms. 

More and more countries are using wind power worldwide, helping the environment greatly. In Denmark, for instance, 40% of its total electricity consumption is provided by harnessing the sustainable energy of wind.