A few miles down the trail, you notice a breeze is picking up. The temperature has dropped several degrees. When you look at the sky, you see clouds are moving in.
Should you keep going? Turn around and head for home? Find shelter as quickly as possible?
“Everybody talks about the weather, but nobody does anything about it,” goes an old saying. Even so, weather is a great subject to talk about with Scouts. What is happening in the sky can give them and you fresh ways for understanding the environment and for deciding whether to put on more sunscreen or dive into a tent.
That breeze and cooling temperatures are caused by a magnificent worldwide weather machine affecting every place on the globe. It is powered by energy from the sun and follows somewhat predictable patterns.
In the Northern Hemisphere, warm air rising over the tropics is pulled north by cold Arctic air sinking and flowing south. The rotation of the Earth tugs that conveyor belt of wind sideways, causing many prevailing weather patterns to move across North America from west to east.
Rising air lifts moisture into the sky where it can form droplets that gather into clouds. White clouds usually aren’t carrying enough moisture to turn into precipitation. Gray clouds are weighted with wetness and might let loose rain, sleet or snow. Tinges of green in fast-moving clouds suggest danger of hail and potential for tornadoes.
Cirrus are wispy white clouds moving high across the sky. They often arrive as fair weather is beginning to change. Cirrus clouds suggest good conditions might last a while longer, but that something is up with the weather system.
Cumulus are the big cotton-ball clouds that children draw and imagine to be in the shapes of animals and famous people. A sky full of them promises fair weather. Watch for shifts in their color and shape, though. Warm afternoon air can lift additional moisture into cumulus clouds, causing them to darken and billow into thunderheads. If you see that happening, seek cover from possible lightning, hard rains and even hail.
Stratus clouds are heavier, lower and have less shape. They cover the sky and often generate rain or snow that can last for hours. A day dominated by stratus overcast could be a good reason to stay inside by a fireplace and read a book.
The more you watch the weather in the areas you go, the sharper your ability to predict what will happen. You’ll see patterns emerging that you can recognize the next time they appear.
That’s been true for centuries as people paying attention to local phenomena noticed clues to changing weather. Some farmers believed that when their cows lay down in a pasture, a storm was coming. There are campers who are convinced smoke going straight up from a cooking fire guarantees stable conditions. See birds roosting in the middle of the day? That can be a warning for you to take shelter, too.
Some weather lore has been around so long that it is part of our vocabulary. “Red sky at morning, sailors take warning,” for instance, relates to the sun’s early rays appearing red because of moisture in the air that could turn into storms. “Red sky at night, sailor’s delight,” suggests good weather after sunset because sunlight from the west, the direction of many weather systems, has been turned red by dust in the sky.
Today, you can visit powerful websites forecasting weather with pinpoint accuracy. That can be a terrific resource for planning before an adventure and for becoming familiar with the prevailing weather patterns of your area.
Encourage Scouts to be aware of clouds, breezes and other natural phenomena. Help them watch for changes and use what they see and feel to predict what will happen next. Understanding weather takes practice and experience, but over time it can become one of the most useful and enjoyable tools in a Scout’s outdoor toolbox.
The BSA Fieldbook has a whole chapter on weather. You’ll also find great info in the Weather merit badge pamphlet.
The International System of Cloud Classification
Beyond identifying the basic shapes of clouds, meteorologists have devised a system for classifying 10 principal cloud types. Starting with clouds that form highest in the atmosphere, they are:
Cirrus: thin, wispy clouds sometimes described as mares’ tails or curls of hair
Cirrocumulus: small cloudlets that resemble ripples or grains
Cirrostratus: thin veil of cloud that covers the sky
Altocumulus: globs of clouds in patches or layers
Altostratus: thin cloud sheets or layers that appear bluish or gray
Nimbostratus: dark layers of ragged clouds, usually carrying rain
Stratocumulus: sheets of lumpy clouds, usually with some dark patches
Stratus: uniform, low layers of clouds that cover the entire sky
Cumulus: large, individual puffy clouds that appear in heaps
Cumulonimbus: large, towering clouds associated with thunderstorms
ROBERT BIRKBY is author of three editions of The Boy Scout Handbook, two editions of the Fieldbook and the newest edition of the Conservation Handbook. Find him at robertbirkby.com