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Not so very long ago---two or three generations at most---predicting the weather was as much art as science, though still based on careful observation of natural phenomena. Chances are good that your grandfather or great-grandfather could look at the sky, perhaps consult a simple glass barometer, and reckon the weather nearly as accurately as today's television weatherman (or woman), nine times out of ten. While fast-moving storms may have taken him by surprise on rare occasions, the accumulated wisdom of a dozen or more generations that had lived much closer to the land (and sea) than we do today would have served him well.
So how did sailors, farmers, and others whose lives and livelihoods depended on the weather---and who lived in an era before satellites, radar, and weather balloons---make sense of a force as huge as the weather? Largely by paying attention to patterns, as it turns out. Though a constantly changing, shapeless swirl of water vapor, temperature, and barometric pressure, "the weather" becomes visible, or observable at least, in the guises of wind, rain (as well as snow, sleet, hail, and fog), and cloud formations. By noticing and remembering conditions prior to rough weather, these old-timers were able to impose some order on their experience of the world and even prepare for impending confrontations with Mother Nature, whether they were three days from land in the North Atlantic or trying to get the hay in before a summer thunderstorm in the heartland.
Though mariners are primarily responsible for the rhymes we remember them by ("Red sky at night, sailors' delight…" and the like), clouds fascinate all who pay attention to them, from the youngest child to the oldest salty dog. Rorschach interpretations aside, clouds do form in patterns that tend to indicate the direction the weather might be moving. Fluffy, cotton-candy-like clouds (known as cumulus to meteorologists) that are primarily horizontal portend fair weather. If these same clouds begin rising up, forming fluffy mountains (cumulonimbus), beware---a thunderstorm may be on the horizon. Similarly, mares' tails---long, thin, streaky clouds known as cirrus---are generally indicative of fair weather, but if they begin to thicken and cover the sky, you can be pretty sure precipitation is on its way.
Often our forebears could tell not only whether a storm was coming but also how severe the storm was likely to be. One indicator of a storm's duration is the amount of notice it gives. Large storm fronts advertise their arrival over a long period---cloud activity will be intense, the wind will often shift direction, and the barometric pressure will drop enough that you can feel the change in the air. Smaller storms generally provide much less notice, blowing in quickly, and then out again just as fast. Similarly, rain preceding wind is often the sign of a more intense storm than the opposite (wind before rain), because major fronts and depressions are usually accompanied by precipitation for a great distance ahead of the center of the storm.
In addition to observing the sky and paying attention to patterns over time, our ancestors also consulted simple yet fairly reliable weather instruments. The basic glass barometer (often referred to as a Cape Cod weather glass or a thunder bottle) in which a volume of liquid, usually colored water, rises and falls in the spout of what looks like a little teapot, is a remarkably effective tool for observing changes in barometric pressure. These changes generally presage a change in the weather, indicating the passage of a front. When the liquid is moving down the spout, indicating higher barometric pressure (the air "weighs" more), expect fair weather. If, rather, the liquid is rising up the spout, the pressure is dropping, and a storm is likely to be on the horizon.
Just as with pressure, it's the direction of temperature change that's useful in predicting the weather. Temperature change occurs steadily every day, warming up as the sun rises, then cooling as it sets; it also changes very gradually on a seasonal scale. But change that's quirky---the temperature dropping steadily all day long even as the sun is climbing higher into the sky, for example, or the temperature rising steadily through the evening---indicates instability and often precipitation. Temperatures that are rising "unnaturally" generally mean light rain is on its way. If the temperature is dropping significantly when it seems like it should be rising or at least holding steady, a cold front is moving in---be prepared for thunderstorms.
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