Introduction to Paraglider Thermalling

Paragliding is the art of flying an un-powered soft wing which is held in shape by ram-air pressure. Paragliders can be launched from hillsides, the sides or tops of mountains, towed aloft by a vehicle, winch or boat, or dropped from a slow moving aircraft or balloon using a D-Bagging launch.

As a Paraglider pilot, the long term goal is to progress to cross country flying. Cross country flights are achieved by finding and using thermals to gain height and continue the flight.

The term "thermal" is given to a mostly invisible tower of air that is rising from the earths surface. Warm air tends to rise, so when a patch of air is heated, it rises through the cooler surrounding air resulting in a thermal column or bubble. This skyward motion of the thermic activity is captured by a Paraglider and used to gain height. Finding new thermals quickly and maintaining a good altitude makes XC easy.

Thermals gather speed, strength and size as they gain altitude(until an inversion is reached). It follows that it is easier to ride a thermal near cloud-base than finding and catching one at low altitude. XC pilots need to constantly be on the lookout for thermal sources. Thermal sources change depending on the angle of the sun and the time of the day.

An example of what I mean is this: A hillside facing the sun late in the morning will be a good source of thermic activity. When that same hillside is in shadow late in the afternoon, it will be the source of sinking air known as catabatic flow. The opposite side of the same hill now the target of the strong afternoon sun, will be popping strong thermal activity. This major idea is transposed to many other potential thermal sources.

Here are the top places to find strong thermals.

1. As described earlier, the sunny side of a hill or mountain.

2. A patch of rocks or dark dirt in an otherwise vegetated area will work well in the afternoon after it has had time to build up heat.

3. Roads (and passing cars can be the trigger)

4. Dark colored roofs and groups of buildings are often productive.

5. Light colored terrain (especially when surrounded by dark lush vegetated terrain) an exception is dark colored dried cotton fields which produce powerful thermic activity.

6. Ridges of hills are a good source of afternoon thermals.

7. Dense vegetation such as trees or a forest supplies good thermic activity lat in the afternoon when the surrounding air has cooled.

8. Magic lift is the less defined lift which just happens. This can be caused by several source of airflow being combined and forced upwards by geographical constraints.

Always keep in mind that thermals need a source of heat and also a point to release from. Some sources offer both functions while others such as a field of dry grass, needs a trigger point such as an adjacent line of trees, a tractor moving across it and so on. Depending on the atmospheric conditions, thermals result in cloud formation. This makes the thermals easier to find.

When we have found and entered a thermal, the next black art is to stay in it. More on that another day.