Mesospheric jet

From Glossary of Meteorology

mesospheric jet

There are two zonal jet streams in the layer known as the mesosphere.

In January, there is a westerly (blowing from the west) jet located at 70 km between 25° and 45°N with a maximum wind of 60 m s-1. There is also an easterly jet of comparable intensity located between 30° and 50°S. In July, the direction of the mesospheric jet in each hemisphere is reversed. The westerly jet in the southern hemisphere in July descends to a somewhat lower level (about 50 km) and has a stronger intensity (about 100 m s-1)