Weather Forecasts - Frequently Asked Questions about weather lore
* What is the calm before the storm?
* Dry cold versus damp cold
* What is good fishing weather?
* When leaves show their undersides, is it a sign of rain?
* Is it colder during a full moon?
* Can you tell the weather from smoke signals?
* Sounds prior to rain
* Winds whistling in winter
* Does a red sky at sunset mean that the next day is going to be an excellent day?
* What does it mean when you see a rainbow in the eastern sky early in the morning?
* Does a ring around the moon at night mean a storm the next day?
* Why "if there is dew on the grass, no rain comes to pass?"
What is the calm before the storm?
I am sure you have heard the expression the calm or lull before a storm. You might ask what is that period of calm or stillness? Imagine an enormous thundercloud approaching. A meteorologist friend of mine likens it to a huge vacuum cleaner, sucking up huge amounts of warm and moist air at the surface from all directions. Pre-existing winds, those not created by the storm, are relatively light, converging or coming together near the surface from different directions. Air at and near the surface moves upward causing a pressure imbalance near the surface - this pressure imbalance pulls more air into the towering thunderstorm. Whereas, the surface winds under these severe updrafts are lulled into an artificial calm with the air moving up, the updrafts well above the surface gain incredible speed - sometimes exceeding 100 km/h or more. Then comes the nasty part of the storm right behind the updrafts - heavy rain and maybe hail, lightning and thunder, powerful downdrafts that hit the ground, strong gusty winds - all quite turbulent compared to the relative tranquillity ahead of the storm itself.
Dry cold versus damp cold
I know many who have experienced cold stress, especially those of you on the Prairies, may take exception to this, but the assumption that dry cold is better than damp cold is largely a myth. Soldiers exposed to severe cold in climate controlled cold chambers did not find damp cold any more penetrating than dry cold, and if you consider the physics of heat transfer, the differences between the two are negligible. But why then do the majority of Canadians prefer dry cold to damp cold? One's perception of comfort or discomfort while exposed to cold air depends on several factors but let's just consider the weather conditions. Cold, dry days have usually sunny skies, high pressure and light winds - weather that is much more pleasing than overcast skies and shivering wind chill. Also soaking up sun's rays only adds to your comfort. So there's good reason to believe that you'll be more comfortable in a dry cold than humid cold, but it's not because of the difference in humidity. Of course, all this assumes one is not perspiring, his or her clothes are dry and it's not raining.
What is good fishing weather?
Ray Kolbun is a firm believer in the saying: "When the wind is from the East, the fish bite the least." In the Northern Hemisphere, stormy low pressure systems rotate counterclockwise with the prevailing winds usually blowing from the east. With the approach of such storms fish apparently head to the bottom of the lake or stream, are less active and refuse to bite. Anglers love to argue over which weather makes fish bite more or less. I've heard it said that:
* Fish hide on sunny days or when it thunders
* A slight ripple of the water and fishing is better
Good fishing occurs with rising pressure, yet I've heard it said fish start biting when the barometer starts to fall. There may be a grain of truth to some of these superstitions. What I do know is that generally fishermen are some of the best at reading the signs of the weather, hoping it will improve their chances. In the end, I suspect, anglers still have no idea why they catch their limit one day and nary a nibble the next. When it comes down to it, there are no sure things, especially not in fishing and in weather forecasting.
When leaves show their undersides, is it a sign of rain?
Several of our users have a similar question, when leaves on the trees turn upside down does that mean we should expect rain in 24 hours? Plants and trees respond in a variety of ways to changes in the weather. One of my favourite sayings is the daisy shuts its eye before rain. It has also been said that before rain, the leaves of trees like the poplar, curl up and show a great deal of their under surfaces. Why is this? Ahead of a local shower or thunderstorm, the air is more moist. The damp air softens the leaf-stalks and allows them to be more easily lifted by the breeze. Also before local showers and thunderstorms, there are always rising currents of heated air which can expose the under-sides of leaves. Further, in our country, prevailing winds are from the west. However, a rainstorm is often preceded by easterly winds. This change in direction will also make the leaves flip over. It is important to remember that leaves are really reacting to weather conditions right now, not changes in the weather over the next 24 or 48 hours.
Is it colder during a full moon?
I receive many questions about the effect of the moon on weather. Here is one: Why does it seem colder around the time of the full moon? Actually, moonlight may warm the earth by a fraction of a degree. Recently, scientists observed that during a full moon, more sunlight is reflected back to Earth, thus slightly warming the planet. The reason why you might think that it is colder with a full moon is because clouds not only hide our view of the stars and moon, but tend to trap and hold in the day's warmth. However, if the sky is clear after sunset, the day's heat radiates to space, chilling the air near the surface. In fact, there is a piece of folklore that says: Cold is the night when the moon shines bright. Remember, the full moon is shining even when obscured by cloud. If the sky is clear, you're more likely to look up and notice the full moon. On such occasions, especially at harvest, the air is likely to be cold and crisp.
Can you tell the weather from smoke signals?
Some people asked if you can tell whether the day is going to be sunny or wet by the way smoke curls around a chimney. Weatherlore says that when chimney smoke sinks upon the roof and falls to the ground it signals rain or snow within 24 hours. In such situations, the dirty particulates in smoke tend to absorb the added moisture in advance of the storm, hence smoke becomes heavier and is dragged down. Thus drooping smoke usually indicates warmer and damper weather. [In dry, sunny, calm weather, a column of hot smoke from a chimney rises straight, and will continue to rise faster and farther as long as it is warmer than the surrounding air. Under persistent high pressure, the air near the ground is usually dry and cool, encouraging a rising plume. So smoke going straight up foretells good weather.] Smoke signals for predicting the weather are becoming less visible nowadays; fortunately, industries are required to remove nearly all of the particulate material that make smoke plumes visible.
Sounds prior to rain
There's a story about some people that could predict weather by the sound of a train whistle.Is that true or not? It's true we seem to hear distant sounds such as train whistles and ringing church bells better before a storm approaches. When the sky is overcast and humid (often the conditions that exist before it rains), you don't get the up and down air currents and strong gusty winds that rapidly break up sounds, so passing sound travels far and wide. There is also a second factor. At times in a widespread rainfall, you find the air near the ground is cooler than the air immediately above. In this stable condition, called an inversion, there is a concentration of sound waves in the lower, colder air. Sounds heading upwards are bent back to earth and combine with those that travel the normal straight course, thereby intensifying the sounds you hear. There's even a piece of weather lore that supports this notion:
Sound travelling far and wide
A stormy day will betide.
Winds whistling in winter
Why is it that in the winter, the wind makes a whistling or moaning sound, whereas in the warmer months, you don't hear those same sounds? First there is more wind in winter - 25% more - than in summer. Part of the effect may simply be that in winter, winds whistle through gaps and cracks around closed doors and windows and open chimneys. Also, in winter, sounds are generally much better heard, largely because there are fewer competing noises like voices and sounds from birds and insects. Further, there are no soundproofing leaves so wind sounds are more audible. Actually, the wind can create a whole symphony of noises, including humming telephone wires and whispering pine needles. As the wind rushes by a wire, bare twigs and even the branches of trees, the air becomes unstable and forms tiny whirls or ripples. These vibrations have a pitch that varies directly as the speed of the wind. It is also well known that the humming of telephone wires is loudest when the wires are tightly stretched as they often are during cold weather.
If it is red sky at sunset, does this mean that the next day is going to be an excellent day?
I wouldn't bet too much on that! The logic behind "red sky at morning, sailors take warning, red sky at night, sailors delight" is that if the sky is red in the morning, any clouds would be to the west, which is the directions from which clouds usually come in from in Canada. Conversely, if the sky is red at night (dusk) the clouds would have departed. Again, don't put too much stock in this - stay tuned to The Weather Network instead.
What does it mean when you see a rainbow in the eastern sky early in the morning?
There is a popular rhyme, "rainbow in the morning, sailors take warning". This rhyme was formulated after many years of sailing observations. Sailors made observations of weather patterns and they noticed that when they saw a rainbow in the early morning, rain was on its way (or very close to happening). This rhyme is about 60 to 70% accurate.
Is there any basis for the belief that a ring around the moon at night means a storm the next day?
The presence of a ring around the moon indicates that there are ice crystals high up in the atmosphere. These crystals are the main components of high-level cirrus clouds, which often, (but not always) are the first clouds to appear when a warm front approaches a given area. Typically, a warm front will be associated with a low pressure system which is commonly referred to as a storm.
Why "if there is dew on the grass, no rain comes to pass?"
When dew or frost forms on the ground it indicates that there are calm winds and clear skies during the night. This is characteristic of strong high pressure systems which generally will bring sunny skies later in the day and no rain or snow. With no cloud cover overnight the surface of the earth is able to cool close enough to its dew point temperature so that water will be able to condense in the form of dew or frost.