WRAL WeatherCenter Blog

Weather before technology

Posted May 11, 2011 1:15 p.m. EDT

Severe weather has played a big role in each of our lives during the month of April here in North Carolina. I don’t know about you, but I have found myself looking up at the sky often these days when rain and storms are forecast, trying to find that next storm brewing off in the distance. Forecasting weather is advanced technology like DUALDoppler 5000 and complicated computer models mixed with just everyday common sense, like being aware of what the weather is doing around you at the time. Meteorologists look at weather differently than most people. We study the science behind what is forecast to happen, and then we monitor the situation as it unfolds. We live in a world of advanced technology to help us do our jobs. Have you ever wondered how people did it back before computers and Doppler radar?

People around the world all looked to the sky to determine that day’s weather or what they could expect tomorrow. "Red sky in the morning, sailor's warning; red sky at night, sailor's delight." "Evening red and morning gray, you’re sure to have a fishing day. Stay at home when the morning sky appears red, but look for a good day’s travel when the evening clouds turn crimson." Even the Bible helped predict the weather. Mathew 16:2 reads "when in the evening you say, It will be fair weather, for the sky is red.' And in the morning, 'It will be stormy today for the sky is red and threatening.'" Each one of these proverbs carries a common theme and has a good rate of accuracy. Let's now look at why.

The science behind these sayings is simple. Usually, weather moves from west to east, blown by the westerly winds aloft. Most of the storm systems we see come in from the west. The colors we see in the sky are due to the rays of sunlight being split into colors of the light spectrum as they pass through the atmosphere and ricochet off the water vapor and dust particles. The amount of water vapor and dust are good indicators of weather conditions. They also determine which colors we see in the sky. During sunrise and sunset the sun is low in the sky, so it transmits light through the thickest part of the atmosphere. A red sky means that the atmosphere is full of dust particles and moisture. We see red, because the red wavelengths are breaking through the atmosphere. When we see this in the morning, it indicates a storm system may be moving to the east. If the morning sky is a deep red, it means that rain is on the way because in order to see such a deep red, the atmosphere must have a high concentration of water.

Did you know that looking at stars is also a way to predict weather? The twinkling of stars is related to relative humidity. Stars on the horizon up to a 40 degree angle will twinkle normally while those stars directly overhead don’t twinkle as much. When the relative humidity increases or high winds disturb the upper air, the stars begin to twinkle above that 40 degrees angle. In the tropics, people know that when this happens the raining season is about to begin.

Overall, people throughout the ages have been quite industrious with using what Mother Nature provided to predict the weather. Even as I write this blog today, science is racing toward another new and great tool to help with weather forecasting. I wonder what people will say about us in the future when they look back in time?