The lower in the startosphere, the more UV that has already been absorbed and therefore the cooler the air. So unlike the troposphere which cools with altitude, the stratosphere warms with altitude. The altitude of the stratosphere can be determined by looking at KNSP external air temperature graphs. We can see the altitude of the stratosphere is not constant. By looking at several flights you can determine seasonal variations.
Winds are affected by landforms and once airborne, there is less interference from the surface.
Winds are not constant with altitude. Jetstreams which reside at the boundaries between polar and temperate air masses can pack winds faster than 200 mph. The temperature differences and the coriolis effect generate these flat tunnels of wind. They typically occur around 35,000 feet, are a few miles deep and can be hundreds of miles wide. Look for maximum winds in the 35,000 foot range of KNSP data.