noun
mass nounCloud forming a continuous uniform layer which resembles stratus but occurs at medium altitude (typically 2 to 7 km, 6,500 to 23,000 ft).
‘The grey layer looks like and should be an altostratus although the fronts look different in the tropical regions.’- ‘An altostratus cloud usually covers the whole sky and has a gray or blue-gray appearance.’
- ‘Where enough light shows through cirrostratus clouds to create shadows, it does not with altostratus.’
- ‘From the ground this altostratus looks white or slightly blue and watery.’
- ‘You were probably looking at the sun or moon through a layer of altostratus clouds.’
Origin
Late 19th century from modern Latin alto- (from Latin altus ‘high’) + stratus.
Are You Learning English? Here Are Our Top English Tips