World News | Curious Kids: Where the hell does the wind come from?

Sydney, 26 February (talk) The short answer is that winds happen because the sun heats some parts of the Earth more than others, and this uneven heating triggers winds. That means wind energy is really a form of solar energy!

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all winds are the same

Wind systems on Earth vary from global-scale trade winds and jet streams to local sea breezes, but they all ultimately depend on the planet being unevenly heated by the sun.

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When the ground heats up and gets very hot during the day, it heats the air above it through a process called heat conduction. This causes the air to expand to occupy a larger volume.

According to the so-called “ideal gas law”, the increase in volume is directly proportional to the temperature.

In other words, heated air is less dense. If this happened to all the air, there would be no wind; the entire air layer would just be a little thicker.

However, if it occurs in the air in one place rather than the surrounding air, the heated air will rise. This is the principle that allows a hot air balloon to remain buoyant in the air: the total weight of the air in the balloon, plus the basket and people inside, must weigh roughly the same as the same volume of cold air outside. balloon.

Without a payload or tether, the balloon will continue to accelerate upwards until it cools down.

A rising hot air balloon doesn’t generate any wind because it’s so small. But imagine if the same thing happened to all the air in an entire city or larger area!

When such a large amount of hot air rises from the surface, other air near the ground must flow sideways to take its place. The larger the area where this happens, the stronger the horizontal wind needs to be to get all the air in place.

This phenomenon means that our daytime sea breezes near the coast can be quite strong, and as the ocean rises, cooler oceanic air flows in to replace warmer continental air.

A similar process brings us monsoons on many days, as the heat in summer is stronger and the heat in winter is weaker, resulting in strong temperature contrasts and winds in summer (usually the opposite in winter).

This, in turn, causes seasonal changes in the prevailing winds, which typically bring rainfall during the warmer seasons in tropical regions such as India and northern Australia.

have some very large wind systems

The largest wind system on Earth is called the atmospheric circulation. They include trade or easterly winds, mid-latitude westerly winds and the Roaring Forties.

These large wind systems happen because the tropics get more sunlight than the poles and (apparently) get warmer. Warm air naturally begins to rise and wants to flow toward the poles, while polar air wants to descend toward the tropics.

Of course, it would take a long time (many days) for the air to travel this far. At the same time, the Earth is constantly spinning, which means that things that try to move in a straight line seem to gradually turn around.

Winds that flow poleward gradually turn to the east, becoming the mid-latitude westerlies (Western means “from the west”).

The low-level winds that blow toward the tropics turn westward and become easterly winds, also known as trade winds because ship captains have used them for centuries to cross the oceans.

The mid-latitude westerly wind is very strong at high altitude, and in some places it is close to 300km/h!

You can see an interactive visualization of all the winds on Earth here. (dialogue)

(This is an unedited and auto-generated story from a Syndicated News feed, the content body may not have been modified or edited by LatestLY staff)