Weather lore
Weather lore is the body of informal folklore related to the prediction of the weather and its greater meaning.
Much like regular folklore, weather lore is passed down through speech and writing from normal people without the use of external measuring instruments. The origin of weather lore can be dated back to primeval people and their usage of star studying in navigation. However, more recently during the Late Middle Ages, the works of two Greek philosopher-poets, Theophrastus of Eresus on Lesbos and Aratus of Macedonia, are known for shaping the prediction of weather. Theophrastus and Aratus collated their works in two main collections for weather lore: On Weather Signs and On Winds. These were used for helping farmers with harvest, merchants for trade and determining the weather the next day.
Astrology and weather lore have been closely interlinked for many years - with each planet often being associated with a weather state. For example, Mars is red and must therefore be hot and dry. Prevalent in ancient Roman thought, astrologists used weather lore to teach commoners of the star and cloud formations and how they can be used to see the future. From this, three main schools of weather lore thoughts developed during the Late Middle Ages as Astrology became more popular throughout Europe. One which related to winds and clouds and had some scientific basis. A second type connected with saints' days possessed doubtful validity but was quite popular nonetheless during the Middle Ages. A third type treated the behaviour of birds and animals, which has been found to be controlled more by past and present weather rather than to be a true indication of the future.
Before the invention of temperature measuring devices, such as the mercury thermometer, it was difficult to gather predictive, numerical data. Therefore, communities used their surroundings to predict and explain the weather in upcoming days.
Today, the majority of weather lore can be found in proverbs. However, much of the weather lore fantasy is still prevalent in today's seasonal calendar, with mentions such as the annual saints' days, the passage of the months, and weather predictions made from animal behaviour. The creation of the astrological signs in Babylonian mythology can also be attributed to the study of stars and its association with weather lore.
Occurrence of "weather"
Weather can be defined as the constant shift in conditions relating to temperature, cloudiness, rainfall etc. at a particular time and place. A significant portion of weather occurs in Earth's middle latitudes, between roughly 30° to 60° North and South.A great percentage of the world's population lives in the equatorial regions, but for the most part, these regions do not experience weather as it is understood by this definition. The Sahara in northern Africa, for instance, is almost uniformly hot, sunny and dry all year long especially due to the non-stop presence of high atmospheric pressure aloft, whereas weather trends on the Indian subcontinent and in the western Pacific, for instance, the monsoonal belt, occur gradually over the very long term, and the diurnal weather patterns remain constant.
Weather folklore, therefore, refers to this mid-latitude region of daily variability. While most of it applies equally to the Southern Hemisphere, the Southern Hemisphere resident may need to take into account the fact that weather systems rotate opposite to those in the North. For instance, the "crossed winds" rule must be reversed for the Australian reader.
Common proverbs
When clouds look like black smoke
Thick, moisture-laden storm clouds absorb sunlight. It gives them an appearance that somewhat resembles black smoke.Red sky at night
A red sky – in the morning or evening – is a result of high pressure air in the atmosphere trapping particles of dust or soot. Air molecules scatter the shorter blue wavelengths of sunlight, but particles of dust, soot and other aerosols scatter the longer red wavelength of sunlight in a process called Rayleigh scattering. At sunrise and sunset, the sun is lower in the sky causing the sunlight to travel through more of the atmosphere so scattering more light. This effect is further enhanced when there are at least some high level clouds to reflect this light back to the ground.When weather systems predominantly move from west to east, a red sky at night indicates that the high pressure air is westwards. In the morning the light is eastwards, and so a red sky then indicates the high pressure has already passed, and an area of low pressure is following behind.
Low-pressure regions
In western European seas, this description of wind direction is an excellent illustration of how the weather events of an active low pressure area present themselves. With the approach of a low, easterly winds typically pick up. These gusty winds can be unpleasant for a number of reasons; they are often uncomfortably warm, dry, and dusty in the summer and bitterly cold in the winter. Northerly winds, which follow around a low, are cold and blustery. Sailing in conditions of northerly winds requires expertise and a boat capable of handling heavy waves. Southerly winds usually bring warm temperatures, and though they may not necessarily feed the fish, they do provide pleasant fishing weather. Wind and weather observations will be different for a low passing to the north of the observer than for one passing to the south. When a low passes to the north, the winds typically pick up from the east, swing to southerly with the passage of the low's warm front, and then switch to northwesterly or westerly as the cold front passes. Typically, if there is any heavy precipitation, it will accompany the passage of the cold front. When a low passes to the south, on the other hand, winds will initially pick up from the east, but will gradually shift to northerly. Overcast skies and steady precipitation often occur as the center of the low passes due south, but skies will clear and winds will gradually become westerly as the low moves off to the east. No observer will experience all the weather elements of a low in a single passage.Calm conditions
Calm conditions, especially with clear skies, indicate the dominance of a high pressure area. Because highs are broad regions of descending air, they discourage the formation of phenomena typically associated with weather, such as clouds, wind, and precipitation. Calm conditions, though, may also result from a circumstance known as "the calm before the storm," in which a large thunderstorm cell to the west may be updrafting the westerly surface wind before it can arrive locally. This situation is readily identifiable by looking to the west – such an approaching storm will be close enough to be unmistakable. In winter, though, calm air and clear skies may signal the presence of an Arctic high, typically accompanied by very cold air, and it is difficult to imagine describing a temperature of –35 °C as pleasant.Ring around the Moon
A halo around the Sun or Moon is caused by the refraction of that body's light by ice crystals at high altitude. Such high-level moisture is a precursor to moisture moving in at increasingly lower levels, and is a good indicator that an active weather system is on its way. Halos typically evolve into what is known as "milk sky", when the sky appears clear, but the typical blue is either washed-out or barely noticeable. This high, thick cirrostratus cloud is a clear indicator of an approaching low. In the coldest days of winter, a halo around the Sun is evidence of very cold and typically clear air at and above the surface. But sun dogs are indicators that weather conditions are likely to change in the next 18 to 36 hours.Humidity indicators
Moisture in the air causes wood to swell, making doors and windows sticky, and salt is a very effective absorber of moisture. With a high level of moisture in the air, the likelihood of precipitation is increased. The magnesium carbonate and later calcium silicate in iodized salt acts as an anti-clumping agent in humid conditions, leading to Morton Salt's umbrella girl logo and slogan "When it rains, it pours".Fog
Fog is formed when the air cools enough that the vapour pressure encourages condensation over evaporation. In order for the air to be cool on a summer night, the sky must be clear, so excess heat can be radiated into space. Cloudy skies act like a blanket, absorbing and reradiating the heat, keeping it in. So if it is cool enough for fog to form, it will probably be clear the next day. Winter fog is the result of two entirely different circumstances. Above the ocean or a large lake, air is typically more humid than above land. When the humid air moves over cold land, it will form fog and precipitation. In northerly climates, ice fog may form when the temperature drops substantially below freezing. It is almost exclusively an urban phenomenon, when the air is so cold that any vapor pressure results in condensation, and additional vapour emitted by automobiles, household furnaces, and industrial plants simply accumulates as fog.File:Caldera afternoon.jpg|thumb|Clouds loom over as seen from Caldera port, in the Pacific coast of Costa Rica.