You're a pilot, so your nonaviating friends are bound to think you have deep knowledge of things meteorological. This may be so, but potential embarrassment can crop up when you haven't seen a terminal area forecast (TAF) in a while, and your neighbor sidles up and asks, "Say, Bob, is it going to rain this weekend?" What are you going to tell him?
At times like these we begin to wonder about all those weather proverbs we've heard. Are they accurate, or just superstitious musings from prescientific times?
A little research turns up hundreds of sayings and ditties (some don't even rhyme!) handed down through the ages. Most of them have their origins in farming, hunting, and sailing, and they rely heavily on pure observation. In other words, the proverbs' authors didn't know why a certain sign meant rain, just that there was a seemingly direct connection between, say, insect behavior and the likelihood of rain. Centuries ago, proverbial signs served as a crude kind of meteorology.
Today, we're still stuck with them. I divide them into four main categories, according to their believability: Makes sense; Lemme think about that; Off the wall; and Duh!
Makes sense
Here are a few sayings that hold up to scrutiny:
A ring around the sun or moon means rain or snow coming soon. The "ring" is the result of the refraction of ice crystals in a high cirrus deck. This is most often associated with the leading edge of an advancing warm front, so yes, you can expect precipitation.
Cold is the night when the stars shine bright. This suggests the clear skies of a high-pressure system, which radiate heat away from the Earth and make cold overnight temperatures. Clear moon, frost soon conveys the same idea.
When dew is on the grass, rain will never come to pass. This one's tied to the previous sayings. Dew forms when temperatures drop to the dew point, so this makes sense because high-pressure systems allow more nighttime radiation cooling.
Rainbow in the morning, sailor's warning; rainbow at night, sailor's delight. Rainbows are caused by light refracting through the back sides of raindrops (that's why rainbows are opposite the direction of the sun), so a morning rainbow (one in the west) means rain is on the way. A rainbow at sunset means rain has passed to the east. This assumes that weather usually travels from west to east — in the northern hemisphere.
Lemme think about that
Many proverbs seem truthful enough, but you wonder sometimes.
Open crocus, warm weather; closed crocus, cold weather. Like tulips and some other plants, crocuses seem to open and close according to temperature and moisture levels.
Sound traveling far and wide, a stormy day will betide. Water is a better conductor of sound than air, so increased water vapor levels should conduct sound better.
If smoke falls to the ground, it's likely to rain. As smoke particles absorb the water molecules from a moisture-laden air mass, they should sink.
When your joints start to ache, rainy weather is at stake. Those with arthritis often swear they can predict rain as lowering atmospheric pressure causes joint fluids to expand.
Birds flying low, expect rain and a blow. Some explain that when high pressure prevails, birds fly higher to take advantage of "optimum air pressure"; with low pressure, birds fly lower. But maybe they're just avoiding lower cloud layers.
Red sky in the morning, sailor's warning; red sky at night, sailor's delight. Almost everyone's heard this one. It, too, is based on weather moving from west to east. When the western sky is clear, you often see a reddish sunset. That's because, at low sun angles, atmospheric particles in the lower atmosphere scatter the bluish wavelengths of light, and allow only the longer, reddish wavelengths to come through. A reddish eastern sky at sunrise means clear weather to the east, so the assumption is that a low-pressure system must soon follow.
Off the wall
Here are a few beauties:
If a dog pulls his feet up high while walking, a change in the weather is coming.
When swans fly, it is a sign of wet weather.
If starlings or crows congregate, expect rain.
Cats scratch a post before wind, wash their faces before rain, and sit with their backs to the fire before snow.
There are plenty more proverbs like this, and most are "explained" by reductions in air pressure or, in the case of the cats, buildups of electrostatic charges.
Duh!
Some proverbs are glaringly obvious:
After black clouds, fair weather.
When clouds sink below the hills, foul weather.
The higher the clouds, the fairer the weather.
Migrating birds fly to avoid a storm.
A northern air brings weather fair.
While I realize that these bits of homespun wisdom in no way fulfill the regulatory requirements as set out in FAR Part 91.103, there's still a place for them in a weatherwise pilot's grab bag of knowledge. You never know when you'll be stuck someplace remote, phoneless, TV-less, and computerless, right?
E-mail the author at [email protected].
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