cirrocumulus High clouds that are small, white and puffy, arranged in groups or lines.
cirrostratus Thin, whitish, veil-like clouds that produce a halo around the Sun or Moon,
but do not blur their outline.
cirrus High, wispy clouds made of ice crystals.
cloud Tiny water or ice particles that are grouped together in the atmosphere.
cumulonimbus Tall, dark clouds that produce thunderstorms.
dew point The temperature at which air is saturated with water vapor, or where the air
has reached 100% humidity.
glaze A layer of smooth, transparent ice that forms when freezing rain or drizzle hit a cold
surface.
hail Pellets of ice or ice and snow that form only in cumulonimbus clouds.
heat index A measurement that combine the effects of temperature and humidity; the
heat index more accurately describes what weather will actually feel like.
humidity The amount of water vapor in the air, sometimes used synonymously with rel-
ative humidity.
nimbostratus Thick, dark, continuous, low clouds that brings continuous rain or snow.
radiation fog Fog caused by the radiation of heat on a cold, windless night.
relative humidity The amount of water vapor in the air relative to the maximum amount
of water vapor that the air could contain at that temperature.
sleet Partly frozen rain or partly melted snow and ice.
stratocumulus Soft, globular, low clouds in groups or lines that rarely bring precipitation.
stratus Low clouds that are continuous and may produce drizzle but no hard rain.
upslope fog Fog that forms from winds that blow up a slope and cool.