Weather Watching Folklore – Myths or Science?

While we have some very sophisticated technology to help predict what Mother Nature is going to do next, the lure of old weather proverbs remain. This brings us to the question of the day: Do those old bits of lore really work?  The answer depends on which bit of lore we’re talking about, as well as where you are in the world.  Some of the weather lore that follows is pretty accurate, letting you forecast local weather even better than the professionals. For each bit of lore in this article, I’ve tried to explain why it does or doesn’t work.

Please keep in mind while reading that most weather phenomena we’ll talk about occurs between 30 and 60 degrees longitude in both the Northern and Southern hemispheres. Weather patterns are pretty predictable and slowly changing in the ecuatorial areas, as well as around the poles.

Red sky at night, sailor’s delight.

Red sky at morning, sailor take warning.

This is possibly the most recognized bit of weather lore out there. There are variations in the UK, Denmark, Italy. Referenced in the Bible, in Matthew 16. Shakespeare even uses it once or twice. There’s good reason for this, since the “Red sky at night” proverb tends to hold true. It has to do with air pressure. Higher air pressure means the air weighs more, pushing contaminants in the air closer to the ground. These particles scatter the shorter wavelengths of light, leaving only the longer, redder ones to color the evening sky.

Furthermore, air needs cooler temperatures for water vapor to condense. Higher pressure it closer to the ground where it’s warmer. If the humidity is high enough, you can still have condensation as things cool off a bit at night, but it usually takes the form of fog or dew, leaving too little water in the air to make rain. So, a red sky in the evening almost always means there will be no rain that night.

The second part of the proverb, about a “Red sky at morning,” isn’t as sure a weather predictor as a red sky in the evening, but it still holds true more often than not. Just as the sky is red in the evening indicates lots of solid particles in the air, a red sky at dawn occurs for the same reason. The higher pressure front has passed and a low has perhaps moved in to take its place. A low pressure front usually brings rain with it, hence the “warning.”

How Fronts Are Formed

Let’s take a moment to look at how a pressure front forms and much of this will hopefully make a little more sense. Hotter air weighs less than colder air because the air particles are more excited and are farther apart. (Remember experiments with gases in high school science?) Since it is less dense it rises, where the thinner atmosphere lets it cool off. Cooler air becomes more dense, because the gases aren’t as excited, and it sinks back towards the earth. This slow process is known as a convection current.

The warmest part of Earth’s atmosphere is here at the surface, but our planet has an uneven surface. This surface roughness is what causes the air to heat unevenly, leading to the high and low pressure differentials that form these convection currents. These giant masses of warming and cooling air are what create our weather. Wind, air pressure, and cloud formation can all be attributed to these pressure areas.

A lot of weather lore, in rhyme format or not, has to do with sensing changes in air pressure.  Allergies tend to be worse just before a heavy rain because all allergens are held closer to the ground. Although not everyone is sensitive enough to detect it, some folks with bad joints will sense the change in weather pressure as well. And those of us with sensitive sinuses can really suffer when a storm front comes through, thanks to intense, painful headaches.

Roosters, Fish, and Other Signs

“When the rooster goes crowing to bed, he will rise with a watery head.”

Animals are sensitive to pressure changes as well. Many birds settle in and roost since they have a difficult time flying in lower pressure weather. Flies seem to be just awful before a rain as well, clustering around windows and doors as though they were trying to get in from the coming wet. Horses and cows seem more agitated, swishing their tails around more than usual to swat away the flies and other bugs that like to bite them.

When the wind is out of the east,

‘Tis neither good for man or beast.

Finally, pack your umbrella on days when the wind blows out of the east, as that’s usually a good sign we’ll see rain before the end of the day. (The opposite is true for those in the Southern Hemisphere.) Winds from this direction often bring low pressure fronts, which are what generally give us bad weather.

It ain’t the heat, it’s the humidity, bub.

A co-worker of my mother’s was fond of saying this. At least in Southeastern Ohio, it’s not really the heat that’s oppressive. It is the amount of water vapor in the air, making us feel like we’d be happier as fish with gills every time we take a breath. Actually, as far as weather is concerned, heat and humidity go hand in hand. When the 6 o’clock news weather forecaster tells us we have 68% humidity, he’s actually telling us the relative humidity, which is how much moisture the air can hold at its current temperature before it is completely saturated. Once the relative humidity hits 100%, a phenomena called the dew point, it will either rain or condense out as dew. However, the relative humidity is dependant upon the air’s temperature. Warmer water can hold more moisture before it has to squeeze some out, which is one of the reasons a hot summer day can be so miserable. The air on a hot day can hold a lot of water before it could be considered full.

As the air cools, either because night is setting or the air is rising up in the atmosphere, it holds less moisture. Particularly in the summer, excess moisture is often lost as dew or fog. This is especially true when there’s cloud cover helping to hold in the day’s warmth. If it is a clear night, rain is often the welcome result of the cooling air.

I know ladies by the score

Whose hair foretells the storm;

Long before it begins to pour

Their curls take a drooping form.

You can’t have rain without humidity, and as we all know, a spell of high humidity makes for the ultimate bad hair day. As the humidity rises, you hair will actually get longer. Curly hair gets frizzy and droopy. Straight hair may gain some curl. Frizzzy hair by itself doesn’t necessarily foretell rain, but the higher the humidity, the more likely it is to rain. Also the higher the humidity, the more likely it is to storm as one weather front violently breaks onto another.

Other signs of increased humidity include chairs that squeak when you sit down and salt that clumps and sticks in the salt shaker. Both have absorbed excess moisture out of the air. Sometimes this excess takes the form of fog or dew, which means we probably won’t have any rain. (Note that this won’t happen if your home is air conditioned, as an air conditioner takes excess moisture from the air.)

If smoke hovers near the ground it is likely to rain.

In order for water vapor to form raindrops, they need to condense around something solid, like dust or smoke particles. Smoke particles can absorb a good bit of moisture, making them too heavy to disburse easily. When smoke heads straight up, it’s going to be a clear day.

When clouds look like black smoke,

A wise man will put on his cloak.

Big, fluffy, cotton candy clouds don’t produce rain, but tall, dark fortress like clouds do signal rain. The clouds aren’t dark because they are bigger, but because they’re full of raindrops.  Of course, you may need to look for other weather signs before you decide whether those raindrops are meant for your head or someone else’s.

When the wind is in the east, ‘tis neither good for man now beast.

When the wind is in the north, the skillful fisher goes not forth.

When the wind is in the west, then ‘tis the very best.

When the wind is in the south, it blows the bait in fishes ‘ mouth.

I am not even going to pretend I like fishing, but this rhyme is also good for understanding weather and wind direction. Winds from the east usually indicate the arrival of a low pressure front and bad weather, which we’ve already established. That’s the direction our weather systems usually travel. Actually, the only good wind direction here is when the wind is in the west, because it would indicate that any potentially bad weather has already blown over. Winds from any other direction usually indicate some sort of weather change, usually for the worse.