Passing Clouds

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"Each day, each hour, clouds reinvent the sky, serene as silk, big as hippos, loud as choo choo trains," writes author John Nichols. "Their Greatest Show on Earth can create a brand new postcard shot faster than I can whistle for help backward."

This time of year the clouds in our sky tend to race across the heavens in thin wisps like sleek airliners, or they come rolling in low and dark and heavy like a freight train. Either way, they seem to be in a great hurry to get somewhere else, or to get away from whatever is coming behind them.

March rushes in as a blustery lion, his mane a changeable mass of water vapors: fog, drizzle, mist and downpour. And, then, just as swiftly as his approach, he slinks back into the jungle across the horizon and the skies clear.

There's no forecasting weather like this, especially when clouds are involved. They play havoc with the best of man's supercomputer-based mathematical weather models.

"The motion of air in the vicinity of clouds is especially complicated," said meteorologist David Randall of Colorado State University during an American Association for the Advancement of Science symposium. "As soon as air enters a cloud its motion becomes turbulent and that, too, is a real problem-causer for mathematical modeling."

Scientists estimate that once a droplet of water evaporates and rises up into the atmosphere it will be airborne for eight or nine days before returning to earth as rain or snow. During that time it may change from water to vapor, snow, or ice several times.

All those changes, combined with the effects of pressure gradients and solar radiation and storm cells, make modeling the weather and predicting its course extremely difficult. Most of the global atmospheric models that meteorologist have relied upon have been savaged by white puffy cotton balls that coalesced into dark vortexes of seething destruction.

"Water's a nightmare," Randall explained. "Within the atmospheric science community, there are some of us who are mathematically inclined and some who are not, and even most who are inclined to deal with modeling flee from the complications of water. It's a dirty mess, mathematically speaking."

If the weather were just about the flow of air and changes in temperature, life would be easier for meteorologists, I suppose, and also much less interesting. It's the wet stuff that makes things chaotic.

The volatile nature of clouds reflects the changeable nature of life in general. The ships or faces or horses that take formation in the skies are fleeting reminders of the impermanence of all things, both in heaven and earth.

Clouds of March, laden with moisture, roll in relentlessly, one dark carload of rain after another. It can seem never-ending, but in a few moments this too shall pass.