When sunlight strikes the ground it warms the ground and the air near it. The warm air near the ground then rises as it expands. What does this process typically result in on the ground?

Point charges q1 = 51 µc and q2 = −27 µc are placed 1.0 m apart, with q2 on the right. what is the force (in n) on a third charge q3 = 19 µc placed midway between q1 and q2? (assume the positive direction is to the right. indicate the direction with the sign of your answer.)