Before we had fancy models, high-resolution satellites and modern-day fluid dynamics, predicting the weather was pretty tough. Oftentimes a “forecast” was based on little more than bird auguries, religious texts, folklore or nursery rhymes. We’ve taken a look at some of the most common weather myths and adages, asking — fact or fiction?

‘Red sky in morning, sailors take warning; red sky at night, sailors’ delight’

We hear it all the time, but have you ever questioned this chunk of weather wisdom’s origin? It turns out that this one came from the bible! In Matthew XVI: 2-3, Jesus Christ is quoted as saying, “When in evening, ye say, it will be fair weather: For the sky is red. And in the morning, it will be foul weather today; for the sky is red and lowering.”

This one has some truth to it. At sea, large storm systems are usually preceded by high, thin, wispy cirrus clouds. Because they’re so far up, they catch the light before sunrise and after sunset, glowing fiery red and amber shades.

In the mid-latitudes where most marine commerce takes place, weather systems propagate from west to east. The sun rises in the east. Its light will glint off the outflow clouds of an approaching storm sweeping in from the west. The result? A crimson-colored sunrise is usually a harbinger of dangerous weather in the offing.

The opposite effect takes place in the evening. A setting sun’s rays fall upon the backdrop of a departing storm, making for a colorful sunset. Sometimes even accompanied by a rainbow, it’s a sign that the worst has passed.

Next time you’re on a ship, think twice as you snap pictures of a stellar sunrise. You may just be in for a rocky ride!

‘If a circle forms ‘round the moon, ‘twill rain soon’

There are two types of circles that can appear around the moon — coronas and halos.

Coronas are much more compact, appearing as a bull's eye of diffuse colors around a nearly full moon.

According to atoptics.co.uk, “they are seen when the clouds are thin enough that each single corona light ray reaching the eye is scattered or diffracted by only one droplet.”

Light passes around droplets, but each colorful component is bent a slightly different amount. The different wavelengths of light no longer overlap, and we see a spectrum of individual colors. How tightly the concentric bands are clustered depends on the size of the water droplets.

A 22º moon halo, on the other hand, is bigger. It looks like a faint ring around the moon. It develops in the same way as its daytime counterpart, the result of refraction within hexagonally shaped ice crystals.

Much as with the red sky mantra, a blanket of high cirrus clouds in the wintertime often heralds foul weather. That easily gives rise to a moon halo. Likewise, coronas are frequently the product of increasing low-level moisture, which usually precedes rain in the warmer months.

‘If clouds move against the wind, rain will follow’

While this saying doesn’t apply in all cases, it usually holds true in the most extreme cases. It boils down to one very important meteorological marvel: wind shear.

It’s a change in wind speed and direction with height. While clouds near the ground may chug along in one direction, that doesn’t mean the winds aloft aren’t streaming in from somewhere else. Wind shear is a key ingredient in the formation of supercell thunderstorms, which rotate. In this type of environment, clouds towering through multiple layers will experience a twisting force. Rotating storms can yield damaging winds, large destructive hail and tornadoes. And rain too.

These earth-shattering tempests spin up in the late spring over the Great Plains. Warm air transport — advection — from the Gulf of Mexico transports moist flow in from the south, with cotton ball clouds riding the breeze. Cold air far above carries cirrus down from the northwest. In between, the winds veer. That pushes clouds in all sorts of directions, often counter to the winds at the surface.

‘Cricket chirps tell the temperature’

While you might not nail the temperature to three decimal places, making friends with a cricket will allow you to ditch the mercury.

The University of Nebraska Lincoln’s Department of Entomology writes that male crickets “chirp by rubbing their front wings together.”

It’s been widely proved that crickets chirp more when it’s warmer out. Scientists have pinned down a relatively simple formula to convert chirp frequency to a temperature reading.

The National Weather Service in El Paso, Tex., recommends counting the number of chirps in 15 seconds, and then adding 40.

That said, crickets are picky — they tend not to be overly chatty when it’s above 100 or below 55. But then again, neither are humans!

‘Your aching joints can foretell a coming storm’

When your great-aunt Suzanne complains tirelessly that the weather is causing her aches and pains, she may actually be onto something. Numerous studies have concluded that there is a correlation between changing weather and an increase in reported pain for patients with rheumatoid arthritis. However, the triggering mechanism behind it remains a mystery to this day.

In one 1990 paper published in the Annals of the Rheumatic Diseases, the authors stated “pain was significantly increased for patients with osteoarthritis on days with rain.

A study released just last year provided the most data yet to make the connection between foul weather and aches and pain.

Women were listed as being more affected by the weather than men.

It’s likely that plummeting temperatures and fluctuations in barometric pressure play a role.

‘Lightning can’t strike twice’

Of course it can! Many times, in fact. The Empire State Building is struck 25 to 100 times every year. The taller or more isolated a structure, the more prone it is to being struck. There’s no reason you can’t have lightning target the same object multiple times.

In fact, if lightning is able to initiate from structure, it may be a sign that the structure is a good conductor of charge and/or sufficiently tall to transport that charge closer to the clouds. It could be more likely to be struck during a thunderstorm.

In the tallest buildings, lightning rods are installed to provide the current associated with a lightning strike a harmless path into the ground, away from anything that could be damaged.

Most commercial airliners are struck once or twice a year.

‘The sky turns green before a tornado’

It doesn’t always, but it frequently does. The same rotating thunderstorms that often give rise to the strongest tornadoes, known as a supercells, also commonly produce giant hail and extreme downpours.

When a potent storm descends on an area, the sky may sometimes take on a shade of blue or deep aquamarine. In Tornado Alley, thunderstorms are often fiercest toward the end of the day, when the sun is low to the horizon. The combination of yellowing hues within an hour or two of sunset and the bluish glow from scattering within the storm can cast the underside of a storm cloud in an ominous, foreboding green.

If you see the sky turn green, it’s a good decision to head indoors.