What causes jetstreams to form at weather fronts? How does the temperature gradient play a part?
There is a front between the relatively dry and cold polar air and the relatively mild and moist subtropical air. Because air is a good isolator, they don’t mix much and form a oblique “wall” at about latitude 60 degrees north and 60 degrees south. The top of our troposphere is called the tropopause. That’s where air stop to sink in temperature with altitude. Clouds don’t rise anymore. The tropopause is nearly twice as high over the equator than the poles. That’s because for an equal pressure, you need much more warm air since it is less dense. Right above the polar front the tropopause then makes a kind of kink where the warm side is higher than the cold one. As a result, the warm side goes over the cold one and the cold one goes over the warm one and … so on! That creates a kind of rotation that is then taken by the coriolis effect and move that kind of horizontal tornado to the west, following the prevailing westerlies of that latitude. So yes, the temperature gradient play a grea
