Weather lore has scientific basis

By Sosimo Ma. Pablico

THE folks in Northwestern Luzon swear that age-old lore is often quite accurate in predicting the weather. But they cannot explain why.

Indeed, there is a scientific basis to weather lore that may explain its accuracy, said Evangeline Galacgac and Criselda Balisacan, two researchers from the Mariano Marcos State University in Batac, Ilocos Norte. Their study on weather lore has earned for them national recognition.

They found that the appearance of clouds, wind direction, humidity, and animal/insect behavior are among the atmospheric and astronomic indicators used by old folks.

For instance, old folks predict rain when the sky is red during sunrise. Galacgac and Balisacan explained that a red sky in the morning is due to the sun shining through dust particles being pushed up by an approaching low pressure system, which brings in moisture. The rain would come when dense clouds in the form of mountains and huge towers are seen in the east or west at dawn.

The researchers said these clouds are cumulus-nimbus clouds, better known as rain clouds or thunderclouds. These clouds always produce a pronounced shower.

They pointed out that high, billowing clouds may build up into cumulus-congested clouds in the mid-morning and develop into cumulonimbus thunderstorm clouds late in the afternoon, bringing rain thereafter.

Some folks said there would be rain a day or two after experiencing a warm night. The researchers explained that moisture tends to hold the day’s heat like a blanket. The more moisture in the air, the more the temperature tends to rise.

Other folks also claimed a good indicator of an approaching storm is the appearance of long parallel band of feathery clouds, called cirrus and cirro cumulus clouds. These clouds appear ahead of an approaching storm or frontal system and can indicate strong winds aloft, the researchers said.

If the cirrus clouds converge toward a point in the horizon, one can say that a storm is present in that direction. A storm has a low-pressure center, which whips up the surface winds to spiral violently toward its center.

If the sky is clear and blue, these feathery clouds will soon disappear in a few hours. But if the sky is grayish, the cirrus clouds thicken and spread to form cirrostratus clouds or are replaced by clouds in sequence of decreasing altitude, indicating that a storm is intensifying and definitely approaching.

The old folks also mentioned that the appearance of the rainbow and moon indicates approaching rain. They said rain will come soon when a rainbow in the west disappears or when a rainbow in that direction is elliptic and appears in the morning.

They added that rain would still come when the crescent moon is tipped on its side.

Actually, a rainbow in the morning is formed when light from the rising sun strikes the water droplets in a raincloud, Galacgac and Balisacan said.

The weather-wise folks observed that bad weather follows a day or two after a ring (called corona in science) is observed around the moon. They said a storm is near when the diameter of the corona is small, a weather disturbance is far from the locality when the diameter of the corona is larger than usual.

Scientific literature points out that, coronas are a result of a diffraction process, which spreads a beam of light into the region behind an obstacle, Galacgac and Balisacan said. Since light waves from the moon are slightly bent around the droplets, these result in a concentration of light in a circle around the moon.

The researchers added that the more humid the air is, the larger the droplets are and, hence, the bigger the corona.

Informants in coastal areas anticipate an incoming storm when the sea roars, high waves or giant waves are seen, and thunder is heard from the sea.

Galacgac and Balisacan explained that tropical cyclones form in regions where there are large and warm oceanic waves. Tropical cyclones begin as a low-pressure center over an ocean or large body of water with strong circulating winds. Giant waves and phenomenal seas, whipped by violent wins spiraling around the center of the storm, are brought to distant shores.

These irregularities are caused by a chain reaction from the immense surface circulation of a storm, especially if it is still over the sea.

To be continued

(Readers may reach columnist at spablico@yahoo.com. For past columns, click http://sundaypunch.prepys.com/archives/category/opinion/harvest-time/ For reactions to this column, click “Send MESSAGES, OPINIONS, COMMENTS” on default page.)

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