Convection currents form when warm air rises and cold air sinks. What causes the warm air to rise and the cold air to sink? A. chemical energy B. activation energy O C. a difference in density D. the law of conservation

the answer is C difference in density because hot air is less dense than cold air so hot air will rise and cold air will fall.

50 inches should be the resultant vector

answer: the exterior temperature of commercial jet planes as they leave the stratosphere and return to the ground increases steadily.

explanation:

the lower most layer of atmosphere is troposphere which extends from 0 to 12 km above the surface of the earth. the temperature initially decreases as distance is increased from the earth's surface. commercial jets fly in lower part of the stratosphere. the stratosphere extends upto 50 km. the temperature in stratosphere starts rising again due to presence of ozone which traps the uv rays.

thus, when the planes leave the stratosphere and return to the ground, the exterior temperature increases steadily.