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.
The expanding air cools, and as this cooling occurs, the water vapor condenses (changes) from a vapor to a liquid. Many tiny water droplets form and a cloud is born.   Conditions have to be just right for clouds to form.louds are formed when water droplets contained in the air rise higher into the atmosphere. There they collect, until a cloud is formed. When water evaporates into the air, it hits the dew point temperature and sticks to smoke and dust particle in the air.