Question

What causes weather to take place?

Answer 1

Weather processes such as wind, clouds, and precipitation are all the result of the atmosphere responding to uneven heating of the Earth by the Sun.

The uneven heating causes temperature differences, which in turn cause air currents (wind) to develop, which then move heat from where there is more heat (higher temperatures) to where there is less heat (lower temperatures).

The atmosphere thus becomes a giant "heat engine", continuously driven by the sun. High and low pressure areas, wind, clouds, and precipitation systems are all caused, either directly or indirectly, by this uneven heating and the resulting heat redistribution processes.

Generally speaking, there are two main main modes of this heat redistribution:

(1) VERTICAL heat transport: Solar heating of the Earth's surface makes the atmosphere convectively unstable, causing vertical air currents to develop. This is what causes puffy-looking clouds, showers, and thunderstorms to form in warm air masses.

(2) HORIZONTAL heat transport: Because the Earth is a sphere, it receives more sunlight in the tropics, and less sunlight toward the North and South Poles. This causes horizontal temperature differences to develop, which in turn causes air pressure differences, leading to wind that transports heat from the tropics to the high latitudes.

Together, this uneven heating in both the horizontal and vertical directions in the atmosphere causes everything that we perceive as "weather".