Wednesday, September 19, 2007

The Missing Guest


On the northbound drive from LAX to SFO last month, tiny pellets fell on the windshield. They appeared dark silver or gold, depending upon the peekaboo sunlight. They rolled UP the windshield. I looked up to see if farmers were spraying some kind of nasty chemicals on the fields from crop dusters. I saw nothing but a few dark clouds off to the east.

It took me a few minutes to figure out that those pellets were actually rain. It had been so long since I had actually experienced rain, that I forgot what it looked like. Additionally, I had never experienced rain in the Prius, which has a sharply raked windshield. The car is so aerodynamic, and the droplets so small, that the force of the wind actually overcame gravity and moved the raindrops UP the windshield.

Technically, it was virga, not rain; the droplets evaporated almost immediately and the road surface was dry.
Wisps or streaks of water or ice particles falling out of a cloud but evaporating before reaching the earth's surface as precipitation.
Anyway, there is much weather excitement in LA because it might actually rain here this week. I took the Prius in to the car wash yesterday to make sure that it would rain. Note, I did not wash the car. Everyone knows that driveway car washing is the largest contributor to groundwater contamination and runoff pollution into the ocean in LA, right?

Asides:
  • No, it is not narcissistic to believe that I can cause rain by getting the car washed. It is merely a statement of fact. The car was washed in preparation for the trip to SFO and it worked like a charm.
  • It was news to me that driveway car washing is so detrimental to the environment. I learned it a few years ago at a groundwater workshop at UCLA's Institute of the Environment.
  • I go to a car wash where they recycle the water. In fact, the stuff coming off cars is so toxic, that the sediment in the water holding tank at the car wash has to be hauled away by a toxic waste hauler. That's right. Road grime is toxic. In addition to the organic alphabet soup of petrochemicals, they also contain lead residue and heavy metals that escape from catalytic converters.
  • Commercial car washes are required by law to recycle water and properly dispose of the sludge. The heavy metals can even by separated and recycled. It makes me feel better about my laziness environmental responsibility.
  • Numerical weather prediction (NWP) models estimate we will get 1/2 to 1" of rain out of this storm. Rob at Are you cereus? was able to show convincingly that NWP models sometimes precipitate out the moisture too fast. They estimate too much rain on the windward side of the mountains and not enough on the lee side. In at least one instance, he was able to convince people to change their model. So don't just complain about bad weather forecasts. Do something about it. Document the bias and show it to the forecasters.

1 comment:

  1. Anonymous15:58

    Didn't know that about car-washing. I thought lawn-watering (because of runoff from ill-aimed sprinklers carrying lawn-care chemicals, etc., to the ocean) and agriculture were the worst culprits.

    However, I've always taken my car to a carwash because I thought doing it by hand wasted a lot of water and knew that California carwashes have to recycle their water.

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