Soaring hawks, like this red-tail, are classified under the genus Buteo. Buteos are hawks and old world buzzards that have broad rounded wings. They use these broad wings to soar on thermal air currents.
Thermals are formed when the ground heats the air that is right above it. As the air is heated it begins to rise. Butoes use this rising air to lift them high into the sky. That way they can conserve energy while flying. Red-tailed hawks get even more use out of the air currents because they fly with their wings slightly uplifted in a "V" shape. This is called a dihedral position and it enables some birds to fly more efficiently.