Question

What is upper air currents or jet streams

Answer 1

jet streams :- The jet stream is a current of fast moving air found in the upper levels of the atmosphere. This rapid current is typically thousands of kilometers long, a few hundred kilometers wide, and only a few kilometers thick. Jet streams are usually found somewhere between 10-15 km (6-9 miles) above the earth's surface.

it is a type of narrow band or a stream

upper air current :- Air currents are concentrated areas of winds. They are mainly due to differences in pressure and/or temperature. They are divided into horizontal and vertical currents: both are present at mesoscale while horizontal ones dominate at synoptic scale. Air currents are not only found in the troposphere, but extend to the stratosphere and mesosphere.

Answer 2

Jet streams are fast flowing, narrow, meandering air currents in the atmospheres of some planets, including Earth.
On Earth, the main jet streams are located near the altitude of the tropopause and are westerly winds .