Using the Clouds to Help Predict the Weather

Long before the development of weather forecast models, people relied upon daily observations to help predict the weather.  That's where a lot of our weather folklore has come from.  On my way into work Wednesday afternoon, I noticed cirrus clouds moving in from the north.  And cirrus clouds can actually give us an indication of what the weather *could* be like later that day, or in the days to come.

Cirrus clouds (wispy looking clouds) are made up of ice crystals that originate from the freezing of super-cooled water droplets.  Cirrus clouds generally occur during fair weather and 'point' in the direction of the air movement.  But cirrus clouds can also be an indication of a warm front moving in.  The leading edge of the warm front (warm air) can extend to nearly 30,000 ft throughout the atmosphere.  As the warm air moves over the cooler air near the surface, it gradually rises throughout the atmosphere.  As this occurs, the warm air cools some and begins to condense.  Since this occurs at levels in the atmosphere where the temperatures are below freezing, cirrus clouds develop.  As the warm front moves closer, those cirrus clouds turn into altocirrus clouds and then stratus clouds, which can eventually turn into rain.

So the next time you look up in the sky and see those thin, wispy looking clouds, may close attention to the forecast.  It could mean rain will soon arrive.