Hello, Kana Here! Wohoo! leggo mate.
xD
Oki so leggo seee...
the characteristics of continental tropical air masses are Cool, moist air
I am not sure about the second one but i think it's forms at high altitudes or covers all or most of the sky but most likely covers all or most of the sky.
Extra for Stratus clouds: More specifically, the term stratus is used to describe flat, hazy, featureless clouds of low altitude varying in color from dark gray to nearly white. The word "stratus" comes from the Latin prefix "strato-", meaning "layer". Stratus clouds may produce a light drizzle or a small amount of snow.
I hope this helps ^^
~ Kana