cloud cover

:  a visible mass of particles of condensed vapor (such as water or ice) suspended in the atmosphere of a planet (such as the earth) or moon

:  something resembling or suggesting a cloud: such as

:  a light filmy, puffy, or billowy mass seeming to float in the air

:  to grow cloudy

:  to become troubled, apprehensive, or distressed in appearance

:  to billow up in the form of a cloud

:  to guard from attack

:  to have within the range of one's guns :  command

:  to hold within range of an aimed firearm

:  something that protects, shelters, or guards: such as

:  natural shelter for an animal

:  the factors that provide such shelter