Sunday, April 7, 2013

Looking at Clouds

courtesy of Joe Brown Digital Photography

Blending the elements of water and air into texture and form, clouds can seem as much a process of the imagination as they are one of nature.  When looking at the shifting shapes of cumulus clouds, I often wonder, am I seeing a reflection of my hopes or my fears?  Is this a heart I see heralding good things to come, or is it a horned face of a devil warning of future woes?  But such musings are as ephemeral as the clouds themselves, and my mind soon turns another kind of wonder, the workings of our atmosphere.

NASA Image
In meteorology, clouds are classified by form  -- wispy cirrus, blanketing stratus and billowy cumulus, and by height -- low, middle and high. Some clouds simply adorn the sky, while others portend precipitation.  The word nimbus is added to the rain-makers; cumulonimbus clouds, more commonly known as thunderheads, can rise to great heights and bring the most extreme weather.   In combination, there are dozens of sub types of clouds, and truly, to the eye, each formation seems as unique as the crystal lattices of snowflakes.

That clouds are composed of gaseous water vapor is a common misunderstanding.  They are actually made of tiny droplets of liquid water, falling ever-so-slowly back to earth.  The height of the clouds is the place where those droplets evaporate back into gas as they fall.  If that happens to be at the surface it is commonly called fog.  Clouds blossom when the atmospheric conditions are such that more droplets are created through the condensation of water vapor than are lost to evaporation.

NASA Image

This blossoming would not be possible without the wondrous property of water to absorb and give off large amounts of energy when it changes from one state of matter to another.  The energy is locked into the molecules of water themselves, and for that reason, it is referred to as latent 'hidden' heat.  This phenomenon is why sweating helps us shed heat -- when the perspiration on our skin evaporates it draws the heat from our skin, causing a cooling effect.  In contrast, when water vapor in the air condenses into tiny water droplets, that stored 'latent' energy is released and results in clouds and storms.

Next time you look up at the clouds, stop for a moment and wonder.  No matter how one looks at them, whether through the spark of imagination or scientific fascination, clouds are truly a phenomena worthy of our musings.


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