Rain clouds stay in the sky because the water droplets within them are small enough that the upward force of the air currents balances or exceeds the downward pull of gravity.
Here's a breakdown:
- Small Water Droplets: The water droplets that make up rain clouds are initially very small.
- Upward Air Currents: Air currents rise through the atmosphere.
- Balanced Forces: These upward-pushing air currents exert a force on the water droplets. According to the reference: "The water droplets are small enough that the upward-pushing force of the air can keep them suspended aloft."
- Gravity's Role: While gravity is constantly pulling the water droplets downwards, the upward force of the air keeps them suspended.
- Eventual Rainfall: The reference continues: "But it can't keep them at the same altitude forever. Any droplet with a large enough radius will eventually get overwhelmed by the downward pull of gravity." As more water vapor condenses, droplets grow larger and heavier. Eventually, gravity overcomes the upward air currents, and the droplets fall as rain.
