water
They are Cirrostratus an Cirrus.
several thousand feet deep
2 feet
A cirrostratus cloud is a high, thin, stratiform made of ice crystals.You can find more information about cirrostratus clouds online or in books at your local library.
Cirrostratus clouds.
Cirrostratus
12-24 hours before a rain or snow storm
when cold air and warm air fall into each others place
A high-level cloud type.
With the exception of rare stratospheric noctilucent clouds, cirrus forms the highest cloud layer (also cirrostratus or cirrocumulus). In the tropics (where the troposphere is thicker, that is tropopause is higher) cirrus can generally occur up to 50-60,000 feet (15-18000 metres), sometimes higher when associated with tropical cumulonimbus anvils. Note that the possible height of cloud varies with location and airmass, so the highest cloud can occur in the tropics, the lower heights (with cirrus possible at 10,000 ft or 3500 m) in polar regions.
Cirrostratus Altostratus Stratocumulus Cumulonimbus Cirrocumulus Altocumulus Nimbostratus Stratocumulus Cumulonimbus