A1: In practice, the USB specification limits the length of a cable between full speed devices to 5 meters (a little under 16 feet 5 inches). For a low speed device the limit is 3 meters (9 feet 10 inches). Q2: Why can't I use a cable longer than 3 or 5m?
Clouds form when moist, warm rising air cools and expands in the atmosphere. The water vapor in the air condenses to form tiny water droplets which are the basis of clouds.
Why do clouds float in the sky even though they have tons of water in them? Clouds are the visible part of a continuous cycle in which water evaporates into the air, condenses and returns to Earth mostly as rain. The cycle starts when the Sun warms the Earth, which in turn, warms pockets of moist air.