The highest psi on earth is in Siberia.
In general, the Siberian High-pressure system begins to build up at the end of August, reaches its peak in the winter, and remains strong until the end of April.
It's genesis at the end of the Arctic summer is caused by the convergence of summer air flows being cooled over interior northeast Asia as days shorten.
Siberian anticyclone, a semipermanent system of high atmospheric pressure centered in northeastern Siberia during the colder half of the year.
The anticyclone forms because of the intense cooling of the surface layers of air over the continent during this season.
Pressure is greatest at sea level and decreases with height.
Air is heaviest at sea level because the air molecules are compressed by the weight of the air above them.
Air becomes lighter farther away from Earth's surface as the air molecules become separated by more space.