Above the subtropical highs in the Northern Hemisphere, and below the subtropical highs in the Southern Hemisphere, winds blow from the west towards the east. These winds are thus called westerly winds, after the direction from whence the winds come.
The westerlies generally blow between 30 ° and 60 ° latitude in both the Northern and Southern hemispheres. The higher one travels into the atmosphere, the more noticeable these westerly winds are.
At the core of the westerly winds lies what scientists call a jet stream. Jet streams are super high-speed winds. Each hemisphere’s westerly has two main jet streams. Closer to the poles we find the polar jet stream. At a slightly lower latitude we find the subtropical jet stream.