The Seven Golden Patterns
1. When clouds get lower, bad weather is more likely. This sign grows more useful with our awareness. Many people notice a low, heavy, leaden sky, but far fewer realize it has been creeping lower for hours, sometimes days. This is about tuning in to trends. Consider the following traditional saying: âWhen the clouds are upon the hills, theyâll come down by the mills.â This makes more sense in light of the trend than the height of the clouds. It is the fact that the clouds are coming from high to low that is significant, not that they have touched the hills.Â
2. The more different cloud types you can spot, the worse the forecast. If we see a lot of different cloud types, it guarantees that the atmosphere is unstable at some levels, which increases the likelihood of bad weather. At this stage we arenât trying to identify cloud types or to name them, just to recognize that there are different types out there.Â
3. When small clouds grow, the forecast gets worse. It sounds so obvious, but most people donât spot this. The casual weather observer notices when the sky has become more cloudy than clear, but not that the small clouds have been growing for hours. The opposite is also true: When clouds shrink, the forecast is improving. We will learn to refine this in many ways, but it is a general pattern that is worth picking up as early as we can.Â
4. Clouds that are much taller than they are wide indicate that bad weather is likely. A very simple pattern that carries an equally simple but powerful message about instability in the atmosphere.Â
5. Spiky or jagged cloud tops are a warning sign of unsettled weather. The shape of the tops of clouds is a map that shows us what the air is doing, and pointed shapes or any sharpness mean that unsettled weather is more likely. The last two patterns lie behind the following lore: When clouds appear like rocks or towers, Earthâs refreshed by frequent showers. It refers to the overall shape of the cloud and the rugged texture, especially near the top. By the same token, smooth, rounded cloud tops are a more positive sign.
6. The rougher the cloud base, the more likely rain becomes. The base of clouds tells us whether rain is imminent. If a cloud has a smooth, flat base, it is not a rain cloud.Â
7. The lower the cloud we use, the shorter the forecast. Low clouds can only reveal what is just about to happen. As we will see, if they start low and grow significantly taller, that is different, but by then they will have reached greater heights and donât count as low clouds. In these patterns, there was a loose progression from long to short forecasts. A lowering cloud base can give you as much as two daysâ warning of bad weather, but noticing the rough base of a dark cloud may give you as little as a few minutes.Â
The Cirrus Family: high, wispy clouds Cirrus clouds are the highest clouds we see regularly. Because of their altitude, cirrus clouds are always ice crystals, and this gives them a pure white color. They have many shapes but almost always appear as a collection of thin, wispy strands. They can look like white cotton candy, feathers, scratches, or hairs. Their height makes them appear to be stationary or moving very slowly, but this is relative: They are actually moving fast. The final golden pattern told us that the lower the clouds, the shorter the forecast. The opposite also holds true: Cirrus clouds offer some of our earliest warnings of change. Cirrus clouds are joined up high by other members of the âcirroâ family. Any cloud with the prefix cirro- is a high, icy cloud.Â
The Stratus Family: layered clouds Stratus is Latin for âflatâ or âlayered,â and this is the defining feature of the stratus family of clouds: wide, flat sheets. They can bring rain but more often donât, but whatever they bring will have constancy. And this is the first sign that the stratus clouds offer: no change for a while. If the sky in the direction that the weather is arriving from is filled with wide, flat stratus clouds, there will be little change for hours, and it will be gradual when it comes. The flat nature of stratus indicates a stable atmosphere.Â
The Cumulus Family: heaped clouds Cumulus clouds come in several forms. In their smallest, kindest guise, they are best known as the fluffy white sheep of fair weather. On their meaner days, they can grow to alarming towers. Whatever their exact shape and size, cumulus are individual clouds that have well-defined bulges above flatter bottoms. If you see a silken white sack of balls dumped on a glass ceiling in the sky, you are looking at a cumulus cloud. If you have ever watched the opening sequence of the The Simpsons, or seen clouds against a blue sky in other cartoons, you were looking at cumulus clouds. The key to understanding cumulus clouds is to recognize that they are bubbling up. But what does that shape signify? All cumulus clouds form as a result of warm air rising through convection because of local heating from below. This is an absolutely critical point. It doesnât matter if youâre looking at a tiny picnic-friendly marshmallow or a towering giant that looks intent on causing trouble: All cumulus clouds indicate that something local has caused the air to warm and rise vigorously. The rounded bulges at the top are a sign that the air is still rising.Â
Cirrostratus: Cirrostratus is high, like all cirro- clouds, but looks distinct and different from cirrus. As the âstratusâ part suggests, this cloud spreads over wide areas. But unlike the normal stratus clouds, which are much lower and totally opaque, cirrostratus covers a blue sky as a milky high veil, imperceptibly thin at first. It is always possible to see through cirrostratusâit rarely hides the sun, the moon, or even the stars very well. Like all cirro- clouds, it is high enough that it is made entirely of ice crystals, which can play with the light of the sun and the moon, creating halosâcircles of light with a bright sphere at the center. Halos aside, cirrostratus, being both high and translucent, is the sort of cloud that is rarely commented upon or even spotted, unless we choose to look for it. It is worth the effort to pick out, though, because it offers much in return. Logically, it is a sign of moisture high in the atmosphere, and this, as we shall see, taken with other signs, can be a useful indicator of change on its way, usually things getting worse. In terms of weather signs, cirrostratus is the most humble, modest cloud. It offers much to those who take the time to get to know and look for it, but it passes over most people without their choosing to take that time.Â
Altostratus: You will have deduced from the stratus part of this cloudâs name that this is another flat blanket. The prefix alto- indicates a middle-height cloud that sits between the high cirrus and the low, friendly cumulus clouds. Altostratus is a wide, often thick, opaque rug of a cloud. It can cover a small country. It sometimes reflects rich colors at the beginning or end of the day, but itâs not known for its beauty. In the whole history of weather watching, I doubt anyone has felt rapture, lost in the wonder of nature, when looking at the shape of altostratus. However, sign readers come closest to that state because we see the part it plays in the broader cast of characters. It is much thicker and lower than cirrostratus, so when it follows that cloud it gives us two of the golden patterns: Clouds are growing and getting lower. Worse weather is on the way.Â
Nimbostratus: Nimbo- comes from nimbus, the Latin word for ârain,â and nimbostratus is simply a stratus cloud that is rain bearing. It is the least cheery cloud in the sky, a dark grey duvet of dreariness. If itâs been raining for half an hour continuously, youâre probably under nimbostratus, and because it is a stratus cloud, it will stretch for many miles. There is little prospect of things improving in the next half hour, either.Â
Cumulonimbus: This is the cloud that everybody recognizes as trouble, but rarely as soon as they might. As the cumulus part affirms, it is a heaped cloud, and as the nimbus part adds, it bears rain. The cumulonimbus is the storm cloud. It is the turbulent dĂŠnouement of an experiment in what happens when air is so unstable it runs riot. Warm, wet air rises through cooler air, lots of vapor condenses, and heat is released much faster than the expanding cloud can lose. It is a cloud with an upward heat accelerator that overpowers the cooling brakes of expansion. The cloud towers up until finally gravity takes over, as growing lumps of ice, water, and air rush down and up in this big engine of trouble. Friction leads to electrical charges, then bang and rumbleâlightning and thunder. Better the devil you know, and later weâll take this troublemaker to one side of the party and get to know him better.
- From The Secret World of Weather, Chapter 3 : The Talk of the Skies, by Tristan Gooley