Answer:
Jet stream is a very fast air stream that occurs in the upper troposphere. Jet streams occur around the earth surrounding it and following an undulating course. These air jets were discovered during the air raids in World War II.
Occurring in the upper levels of the troposphere, this current is of great importance to aviation and can be harnessed to provide fuel economy to the aircraft that penetrate them by taking advantage of the momentum provided by their intense winds. There are two types of jet stream: the subtropical jet, with higher altitude being found between latitudes of 20 ° and 30 °; and the lower altitude polar jet, being generally located between the circumpolar region and the average latitudes (40 ° -70 °). Regardless of the type, jet streams form a boundary between a cold air mass and a hot air mass.