1 \u2013 Water vapour is practically always present in the air in various quantities depending on conditions. When warm air rises , it expands and cools. Cool air can\u2019t hold as much water vapor as warm air , so some of the vapor condenses onto tiny pieces of dust that are floating in the air and forms a tiny droplet around each dust particle. When billions of these droplets come together they become a visible cloud.<\/p>\n\n\n\n
2 \u2013 A cloud is a visible mass of condensed water vapour .<\/p>\n\n\n\n
3 \u2013 Clouds move with the wind , sometimes traveling at more than 150 kilometre-per-hour.<\/p>\n\n\n\n
4 \u2013 While there are a wide variety of cloud shapes and sizes , they are all made of the same thing: large collection of very tiny droplets of water or ice crystals.<\/p>\n\n\n\n
5 \u2013 There\u2019s plenty of water vapour in the atmosphere , but we can\u2019t see it.<\/p>\n\n\n\n
6 \u2013 We only see clouds because the water has condensed into stable enough droplets that diffract and disperse light.<\/p>\n\n\n\n
7 \u2013 The average cloud droplet is .02 mm in diameter , about five times smaller than the thickness of a sheet of paper. These droplets condense to form clouds up to 14 miles tall, which would be the same height as fifty Empire State Buildings.<\/p>\n\n\n\n
8 \u2013 Have you ever watched a cloud long enough to see it expanding outward , or looked away for a moment only to find that when you look back its shape has changed. Clouds are ever-changing thanks to the processes of condensation and evaporation.<\/p>\n\n\n\n
9 \u2013 Even though clouds float in the air , a single cumulus cloud can weigh hundreds of thousands of tons.<\/p>\n\n\n\n
10 \u2013 Cumulonimbus clouds , which are up to 10 times denser and 1,000 times larger than cumulus clouds , could weigh as much as one million tonnes.<\/p>\n\n\n\n