When birds remain airborne and moving without flapping their wings, they are gliding downward with maintaining thrust
Birds are lightweight, because they have got the capability to clasp the wind in their wings. When the birds remain in the air but not flapping their wings, they are gliding across the wind. Birds have their wings open, so it makes them lighter across their whole body, and then it slowly glide.
They are gliding on updrafts or rising currents of air. Air close to the earth is heated by the sun and this causes it to rise. Warm air is less dense than cold air so it will rise. Birds seem to glide because the gravity force acting on the animal as it flies is equal by the rising column of air. This is called soaring. The definition of soaring is: rising very quickly to a high level. For example: A soaring California Condor spreads its primary feathers, so each acts as a small, and high-aspect-ratio wing. This reduces turbulence at the wingtips and lowers the stall speed
Birds also use the thermal uprise where the rising columns of air caused by the uneven heating of Earth's surface from solar radiation.
Grade: 9
Subject: physics
Chapter: birds
Keywords: physics, birds
