Science, Tech, Math › Science How High In the Sky Are Clouds? Share Flipboard Email Print Marta Nardini / Getty Images Science Weather & Climate Understanding Your Forecast Storms & Other Phenomena Chemistry Biology Physics Geology Astronomy By Tiffany Means Meteorology Expert B.S., Atmospheric Sciences and Meteorology, University of North Carolina Tiffany Means is a meteorologist and member of the American Meteorological Society who has worked for CNN, the National Oceanic and Atmospheric Administration, and more. our editorial process Tiffany Means Updated March 19, 2018 Have you ever looked up at the sky while cloud watching and wondered exactly how high above ground clouds float? A cloud's height is determined by a number of things, including the type of cloud and the level at which condensation happens at that particular time of day (this changes depending on what the atmospheric conditions are). When we talk about cloud height, we have to be careful because it can mean one of two things. It can refer to the height above ground, in which case it is called the cloud ceiling or cloud base. Or, it can describe the height of the cloud itself -- the distance between its base and its top, or how "tall" it is. This characteristic is called cloud thickness or cloud depth. Cloud Ceiling Definition Cloud ceiling refers to the height above the earth's surface of the cloud base (or of the lowest cloud layer if there's more than one type of cloud in the sky.) (ceiling because it is the Low clouds, which include cumulus and clouds, can form anywhere from near the surface up to 2,000 meters (6,500 feet). Middle clouds form at altitudes of 2,000 to 4,000 meters (6,500 to 13,000 ft) above ground near the poles, 2,000 to 7,000 meters (6,500 to 23,000 ft) at mid-latitudes, and 2,000 to 2,600 meters (6,500 to 25,000 ft) at the tropics. High clouds have base heights of 3,000 to 7,600 meters (10,000 to 25,000 ft) in polar regions, 5,000 to 12,200 meters (16,500 to 40,000 ft) in temperate regions, and 6,100 to 18,300 meters (20,000 to 60,000 ft) in the tropical region. Cloud ceiling is measured using a weather instrument known as a ceilometer. Ceilometers work by sending out an intense laser beam of light into the sky. As the laser travels through the air, it encounters cloud droplets and is scattered back to the receiver on the ground which then calculates the distance (i.e., the height of the cloud base) from the strength of the return signal. Cloud Thickness and Depth Cloud height, also known as cloud thickness or cloud depth is the distance between a cloud's base, or bottom, and its top. It isn't measured directly but rather is calculated by subtracting the altitude of its top from that of its base. Cloud thickness isn't just some arbitrary thing -- it's actually related to how much precipitation a cloud is capable of producing. The thicker the cloud, the heavier the precipitation that falls from it. For example, cumulonimbus clouds, which are among the deepest clouds, are known for their thunderstorms and heavy downpours whereas very thin clouds (like cirrus) don't generate any precipitation at all. More: How cloudy is "partly cloudy"? METAR Reporting Cloud ceiling is an important weather condition for aviation safety. Because it affects visibility, it determines whether pilots can use Visual Flight Rules (VFR) or must follow Instrument Flight Rules (IFR) instead. For this reason, it is reported in METAR (METeorological Aviation Reports) but only when sky conditions are broken, overcast, or obscured.