These warning signs for bad weather are not fail proof but they may come in useful, whether to predict when to take in clothes from the line or in making an educated guess on possible hiking conditions.
The Mechanics of Bad Weather
A cold front is the leading edge of a moving mass of air that is heavier, colder and drier than the air it is moving into, whereas a warm front is the edge of a mass of lighter, warmer, moister air. Cold fronts push underneath warmer air, lifting it up and causing it to condense into clouds.
A high-pressure system is generally the result of the dense air of a cold air mass falling toward the earth, whereas a low-pressure system is the result of a warm air mass rising. As the warm air rises, it cools and forms clouds and possibly storms, so low pressure systems are associated with rain.
Cold fronts move quickly, and so they are often responsible for storms and tornadoes. While a warm front approaching may cause rain as it rises over an existing cold air mass, warm fronts are generally not so violent. Other physical precursors of stormy or rainy weather include an increase in humidity, which is the amount of water in the air, and winds that have changed direction.
Predicting the Weather by Watching the Sky
One of the simplest and most well known ways of predicting bad weather is by the saying ‘red sky in the morning, sailor’s warning; red sky at night, sailors delight’. However, this may only be useful in the Northern Hemisphere where bad weather generally moves from west to east.
A red sky at night occurs because the setting sun is only able to shine on clouds in the east if there are no clouds in the west to block its rays. A red morning indicates that there are clouds in the west to shine on, which will pass overhead on their way east.
Another well known saying is ‘mackerel sky, mackerel sky; not long wet, not long dry.’ A ‘mackerel sky’ is a sky dotted with cirrocumulus clouds, which look like scales. They can indicate that a low pressure system is on its way, bringing rain and faster winds.
Halos are another warning sign that bad weather is on the way. A halo around the sun or the moon is caused by light reflecting off ice crystals, generally found in cirrostratus clouds. This type of cloud can indicate a warm front is coming, and that rain or snow might be expected in 12 to 24 hours. The brighter the halo, the more likely it will rain.
If there seem to be fewer stars out, it might also be a sign of a storm coming. As the air in the atmosphere grows more turbulent it is more difficult to see dimmer stars. Contrails (the long, thin clouds left by airplanes) can also predict the weather. A contrail that disappears quickly is an indication that dry weather will continue. The longer it stays visible, the more likely it is that rain is on its way.
Other Means of Weather Prediction
When the wind changes direction it is said to be either backing or veering. Leslie Alan Horvitz recommends in The Essential Book of Weather Lore (2007) that a person point at where the wind originally came from, and then where it is currently coming from. If his or her hand moved counterclockwise, the wind is backing which forecasts a coming storm. Also, if wind is coming from the direction of a rainbow, it is probably blowing rain with it.
Smoke can be another predictor of bad weather. If smoke from a chimney is flowing down, or sitting low, it is probably due to a cold front moving in, or due to the smoke particles absorbing water from high humidity and becoming heavier. Both of these are signs of possible rain or storms. If the smoke is also curling, it might be a sign of changing winds.
Human hair can indicate the amount of humidity in the air. When there is high humidity, which might indicate a storm is on the way, curly hair will droop a little, and naturally straight hair might curl a little. Taking a look at a cup of coffee can predict foul weather. When there is low air pressure, which is an indication that rain might form, the surface of the liquid becomes slightly convex, and bubbles will move to the edge of the cup.
There is no sure means of predicting the weather, and while the weatherman might get it wrong sometimes, he will always be the best source of information. However, knowing the signs of approaching bad weather might come in handy one day, if for nothing else than to impress friends and family.
Rachel Sawaya - Rachel Sawaya is a freelance writer from New Zealand (who also has US citizenship), and currently lives in Auckland, the big smoke of New ...
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