METEOROLOGIST JEFF HABY
For this writing we look at the situation in which no clouds occur that is called clear skies. Clouds require just two ingredients which
are lifting and saturated air. If one of these is lacking, then clouds will not develop. The air can be very cold or hot and it can be
very moist or very dry and any combination of these and clouds may not form. When forecasting for no clouds, the primary ingredient
to look for is sinking air throughout the troposphere. Pressure systems such as a subtropical high or polar high can produce
sinking throughout the troposphere. The late morning hours is sometimes a good time to have clear conditions. The early
morning may have fog or low clouds which can mix out to clear skies later in the day. Scattered afternoon clouds are very
common from warming and convective mixing during the day. The late morning is a good time frame between these events. It of
course can be the case that the entire day is cloud free if there is strong sinking in place and the air is fairly dry at
all levels. Getting stuck under a strong ridge can produce day after day of sunny cloud free weather. It can be surprising
difficult in some places to get a completely cloud free day (no morning fog/low stratus, no afternoon fair weather cumulus,
and no cirrus sneaking overhead). A completely cloud free day is a good indication the air is dry at all levels and there
is sinking throughout the troposphere.
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