<h2>Right answer: Cool and warm air masses meeting near the equator</h2>
Subtropical Jet Streams (STJ) are formed near air masses that, being adjacent, register significant differences in temperature. Therefore, these winds are the product of hot and cold air masses that collide near the terrestrial equator.
On Earth, this phenomenon is due to a combination of the rotation of the planet on its axis and global warming due to solar radiation.
In this sense, the subtropical jet stream is constituted by a strong western wind current. In winter, this current surrounds the northern hemisphere in the form of a discontinuous undulating current near the 30º North parallel. While, during the summer, the jet stream moves to the north and weakens, being located in the vicinity of 40º north latitude.
In the southern hemisphere, the STJ varies little in altitude and is between 25º and 30º south latitude during winter and somewhat more in summer.
It should be noted that this phenomenum, on average, is stronger in the western Pacific region than anywhere else in the world. This is mainly because the highlands of the Himalayas and Tibet interrupt and divert the air flow generally from the west in the upper troposphere.
