Sunset. at sea level...ermmm very high...hihihihi...dunno la. can't remember.
Bacteria that live in clouds may have evolved the ability to promote rainstorms as a way to disperse them. These microbes called ice nucleates are found in rain, snow, and hail throughout the world.
A cloud is a visible mass of droplets or frozen crystals floating in the atmosphere above the surface of the Earth or another planetary body. A cloud is also a visible mass attracted by gravity (clouds can also occur as masses of material in interstellar space, where they are called interstellar clouds and nebulae.)
On Earth the condensing substance is typically water vapor, which forms small droplets of ice crystals, typically 0.01 mm in diameter. When surrounded by billions of other droplets or crystals they become visible as clouds. Dense deep clouds exhibit a high reflectance (70% to 95%) throughout the visible range of wavelengths: they thus appear white, at least from the top.