What are winds?
A 'wind' is simply the flow of a huge amount of air, usually from a high pressure-area to a low-pressure area.
How are winds formed?
Typically, this begins with the sun’s radiation, which is absorbed differently on the earth’s surface. The earth's surface is heated differently because of scenarios like cloud cover, mountains, valleys, water bodies, vegetation and desert lands.
As a result of this uneven heating, there are bound to be earth surfaces that vary a lot in temperature. Air on surfaces with higher temperatures
will then begin to rise because it is lighter (less dense). As the air rises, it creates low atmospheric pressure. Air on surfaces with cooler temperatures sink (do not rise). The sinking creates higher atmospheric pressure. This behaviour or warm gases or liquids moving upward and being replaced by cooler particles is called Convection. The energy moving during convection is called convectional current.
Important: Hot air rises and cool air sinks. This brings about spatial differences in atmospheric pressure, caused by uneven heating.
Let us see this illustration below showing pressure and wind direction:
In the diagram above, notice how cool air falls, resulting in high pressure, and moving towards regions of low pressure.
Anywhere and each time there are differences in atmospheric (air) pressure, there will be a wind, because air will move from the high-pressure area to the low-pressure area. It also means that winds may be even stronger where the difference in the air pressure is greater.
A good example is how tropical depression forms, where warm air over hot tropical waters rise, and high-pressure cold air quickly rushing to fill the space.