So much for formic diviniation

Ants seem just as good at predicting rainfall as Environment Canada. Mind you, it’s not like they scratch a message in the dirt as to when the first drop will fall nor do they indicate where.

Not a message I know how to read, anyway.

The weather service now says rain could happen Saturday.

Were I to track it scientifically instead of half-assed, I’d be keeping a log of the dates and times I saw the ant piles and the dates and times rain fell to see if there’s any correlation between when ants start piling dirt around their holes and when the skies open and drop their pay load.

Rain was making FARK headlines earlier in June, actually. I read an interesting article at ScienceNOW about the speed rain falls and why some drops manage to exceed what ought to be their speed limit. A team working out of the University of Mexico has been working on this for a while.

Over several years, the team clocked about 64,000 raindrops falling in Mexico City. The researchers measured their sizes and velocities only in extremely calm conditions, so the wind that often accompanies rain could not skew the data. They found that some drops plummeted faster than the so-called terminal velocity for their size–the speed, based on a well-established scale, at which air resistance counteracts the accelerative force of gravity.

Like the speed of light, the terminal velocity should be an absolute limit. But in a paper in press at Geophysical Research Letters, the team reports many observations of so-called superterminal drops, which form when larger drops collide and break up into bunches of small drops. Those smaller drops can then travel for a time as fast as the larger drops. For example, drops with a diameter of 100 micrometers are supposed to be limited to a terminal velocity of about 30 centimeters per second. But the researchers observed such drops hitting the ground at 3 to 4 meters per second.

How many feet is that? Check a converter. 30cm is a little more than a foot so there’s a bit more than three feet in a meter. 3.24 feet, apparently.

Anyway, the rain researchers found all this to be worth their time and effort.

“What surprised us was not so much seeing the superterminal drops,” says physicist and co-author Raymond Shaw of MTU, “but seeing the deeper, compelling patterns.” He explains that as rain falls harder, the fraction of superterminal, or speeding, small drops increases. At the same time, the proportion of the bigger drops decreases. That result, Shaw says, is “consistent with the notion that large drops break up to produce a swarm of speeding satellite droplets.”

Shaw says there’s a practical side to the research. “Weather forecasting models depend on simplified theories of how raindrops grow, [so] the more we understand about the interactions between drops, … the more we can improve our ability to predict whether it will rain on tomorrow’s picnic.”

Good to know. No more of this dithering in the dirt divining ant business (unless it works).

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Canadian Atheist Basically ordinary Library employee Avid book lover Ditto for movies Wanna-be writer Procrastinator
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