Thermal flying parachute.

When the sun warms the ground will warms. It will warm some features such as rock face or large buildings and these set off thermals which rise through the air. Some times these may be a simple rising column of air, more often. They are blown sideways in the wind and will break off from the source with a new thermal forming later. Once a pilot finds a thermal, he begins to fly in a circle, trying to center the circle on the strongest part of the thermal core. Where the air rising the fastest. Most pilots use a vario altimeter. which indicates climb rate with beeps or a visual display to help core in on a thermal. The technique to core a thermal is simple turn tighter as lift decreases and turn less as lift increases. The ensures you are always flying around the core. Often there is strong sink surrounding thermals and there is often also strong turbulence resulting in wing collapses as a pilot tries to enter a strong thermal. Once inside a thermal, shear forces reduce somewhat and the left tends to become smother. Good thermal flying is a skill which takes time to learn but a good pilot can often care a thermal all way to cloud base.