Question

Why the Earth rotation induces weather conditions around us?

Please, for better understanding I need a detailed description. May be some examples in nature, schemes, and some description based on basic relations. I want to understand it very well. Would be nice to get some additional sources to read (books or articles).

Answer 1

The Coriolis effect is an apparent force caused by the rotation of the Earth. This effect deflects winds in the same way that drawing a straight line on a rotating piece of paper. You move your pen straight but the line is curved.

The reason that has such a huge effect on climate is that without Coriolis there would be no high or low pressures centers, just a uniform pressure.

Air wants to flow from areas of high pressure to areas of low pressure, which just makes sense. The thing is, if there was no outside effect then the pressure gradient cause by the different pressures would result in a pressure gradient force. This force moves the air from high pressure to low pressure. However, as the air is moving the Earth is also rotating. This causes the air to deflect so that it slowly rotates around and inward toward a low and around and outward from a high. As such low pressures are not immediately filled and pressures do not easily balance out.

Without Coriolis wind would be unidirectional, heat would advect quickly and there would be nearly uniform pressure around the world. Deserts would get rain as there would be no Hadley cells. Rainforests would get less rain as the systems simply wouldn't form and precipitation would be close to uniform around the globe.

As the Earth revolves around the sun, its axis is tilted from perpendicular to the plane of the elliptic by ~23.45 degrees. It is on this axis that the earth rotates every 24 hours. Since the axis is tilted, the effects of revolution of the Earth is different for different parts of the globe.

Certain areas are tipped towards, or away from, the sun at different times of the year. This tilting causes the four seasons of the year. This tilting also creates opposite seasons in the Northern and Southern Hemispheres.

It was mentioned that the tilt of the Earth's axis combined with the revolution of the Earth causes the seasons as we know it to change and occur. Currently, this tilt is at an angle of approximately 23.5 degrees.

However, the angle/degree of this tilt is known to change over time. It can be at a maximum of 24 degrees and a minimum of 22.5 degrees.

When the Earth reaches this minimum angle, it plunges the Earth into an ice age. This cycle of tilt, also known as Earth's wobble, occurs in 40,000 year cycles, which leads to periodic ice ages that occur once ever 100,000 years as it takes.

So it's thanks to the specific tilt we are at now combined with the revolution of the Earth around the sun that leads to the seasons and changes in temperature that we experience.

Taking an example of wind current

The global air circulation and the Coriolis Effect transfer warm air from low latitudes and cold air from high latitudes as wind moves from high pressure to low pressure. These global wind and pressure belts are important to Earth's climate, and determine the local geographical pattern of precipitation and temperature.

Yet, for small, local weather systems such as thunderstorms, the wind will flow directly from high pressure to low pressure and is not affected by the Coriolis Effect.