Brewer-Dobson circulation is a model of atmospheric circulation, proposed by Alan Brewer

Alan West Brewer

Alan West Brewer was a Canadian-English physicist and climatologist. Born in Montreal, Canada and raised in Derby, England, he earned a scholarship to study physics at the University College of London. He received his M.Sc. there, and began to work for the Met Office in 1937...

 in 1949 and Gordon Dobson in 1956, that attempts to explain why tropical air has less ozone

Ozone

Ozone , or trioxygen, is a triatomic molecule, consisting of three oxygen atoms. It is an allotrope of oxygen that is much less stable than the diatomic allotrope...

 than polar air, even though the tropical stratosphere

Stratosphere

The stratosphere is the second major layer of Earth's atmosphere, just above the troposphere, and below the mesosphere. It is stratified in temperature, with warmer layers higher up and cooler layers farther down. This is in contrast to the troposphere near the Earth's surface, which is cooler...

 is where most atmospheric ozone is produced. It is a simple circulation model that posits the existence of a slow current

Air current

Air currents may be caused by differences in temperature, pressure, or impurity concentration. Temperature differences can cause air currents because warmer air is less dense than cooler air, causing the warmer air to appear "lighter." Thus, if the warm air is under the cool air, air currents will...

 in the winter hemisphere

Sphere

A sphere is a perfectly round geometrical object in three-dimensional space, such as the shape of a round ball. Like a circle in two dimensions, a perfect sphere is completely symmetrical around its center, with all points on the surface lying the same distance r from the center point...

which redistributes air.