Every wonder how airplanes fly? It's all about air pressure! The air molecules below the wings of the plane are pushing UP on the wings with more force than the air molecules and above the wings are pushing down. The difference is enough to overcome gravity's pull towards the Earth allowing the airplane to lift into the air. The faster the airplane moves forward, the higher it flies! Bernoulli's principle explains how a really heavy airplane gets lifted into the air.
Check out this video to learn about Bernoulli's Principle.