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.
Cirrus clouds have actually been spotted as well! In addition to forming on Earth, cirrus clouds can form on planets like Mars, Saturn, Jupiter, Neptune and Uranus! Although a cirrus clouds appears to be very flat and wispy, the thickness of a cirrus cloud is actually about 1.5 km! How do cirrus clouds form? Cirrus clouds are formed at very high altitude. When air masses reach these heights, the temperature drops drastically. These cold temperatures cause the moisture in the air masses to condense and actually freeze into ice crystals. This occurs above 8000m. Masses of ice crystals are visible to the human eye as a cirrus cloud.