Rain is a Local Phenomenon

Date: August 4th, 2011
Time: right around sunset
Place: looks like Glendale, AZ from here

The image above was captured during one of our typical monsoon rainstorms. It shows clearly how the rainfall can be localized over just a few square miles. The physical position of the rain can shift in any direction while it remains a tight downpour, almost like a moving waterfall from a cloud (which it is).

Same is true of most weather phenomena: snow, hail, sleet, fog, wind, etc. What we’re talking about here is what meteorologists call mesoscale effects (10-100 km), as opposed to microscale or global effects.

I recall when, as a child, our family was driving north along the shore of Lake Michigan. We were on our way to visit my grandparents and driving through a heavy downpour. Suddenly, we drove completely out of the rain. It just stopped abruptly, and the Sun was now visible. I found that quite curious, and asked my Dad “What’s up with that?”

His answer was simple. “Well,” he said, “just ’cause it was raining back there, doesn’t mean it’s raining everywhere.” I had to think about that for while, and of course it made perfect sense. It was just the first time I recall experiencing that effect. It ain’t gonna happen too often when you’re just walking, but at the speed of a car, you can easily get out of the weather in a matter of seconds. Tornado chasers do it all the time.

How a Sunset can be Violet or Indigo
The Perseid Meteor Shower