Clouds can provide us with valuable information; they are great indicators of wind speeds and directions as well as visual clues about thermal activity, strength and other atmospheric conditions. Cumulus clouds are generated by warm air rising and bringing moisture up to its condensation or “dew point.” Cloud development will vary greatly depending on the humidity. In dry areas, you rarely have clouds unless a moist air mass moves in. In humid areas, there can be abundant cloud development, but their presence won’t necessarily translate to abundant lift. Here are some generalities to follow when looking at clouds. Clouds generally start out as wispy areas and grow until the edges are crisp, then become wispy as it deteriorates. If the clouds are wider than they are tall, the lift is likely moderate. If the clouds become taller than they are wide (Marge Simpson hair-doo), they indicates stronger or extreme lift.
If clouds are growing tall early in the day, there is a good change they will over-develop and become nimbus (rain or thunderstorms). If clouds become nimbus and produce rain or virga (Variable Intensity Rain Gradient Aloft), they can generate a gust front or micro-burst. These can cause winds well over 30 mph with severe turbulence. With excessive lift, you may also experience “cloud suck”, where the cloud has started drawing air in to feed itself. Anytime you are nearing the bottom of a cloud you should take precautions to avoid being drawn into it. In most airspace categories (see FAR 103), you are to keep 500 ft of clearance below clouds. As you get near this altitude, it is wise to start widening your turn radius to find the edge of lift, this will help you judge when you should leave. If you are in 1000 fpm of lift and are within 500 ft of the clouds base, you are likely to enter the cloud after one or two more turns. Also keep in mind that if the cloud is building as you are coming up to it, it can quickly develop and encompass you. Not only is it illegal for ultra-light aircraft to fly in clouds, because visibility is low, it’s easy to get vertigo and become disoriented making it difficult to control the glider. It may also be turbulent at the base of a cloud or inside it.