Composition of the
atmosphere
Composition of the Atmosphere
▪ Composition = what something is
made of.
▪ “Air” is all around us and it
behaves often like a liquid- it
flows, moves, and causes things to
happen (weather!)
▪ Air = mixture of dozens of types of
gases.
▪ Air has MASS!! This means it can exert a
FORCE (push) on you!
▪ The air that surrounds the planet is held in
place by gravity and is
called our atmosphere.
▪ Gravity becomes less and less
as you move away from Earth.
▪ As a result, there are fewer and
fewer molecules as you move
away from the surface.
Air!!!
▪ The air around us is 78%:
NITROGEN
▪ 21% of the air around us is:
OXYGEN
▪ The remaining 1% is a mixture of all other
gases:
Carbon dioxide, helium, argon, neon,
hydrogen…
Water Vapor
▪ Water is present in gas form in the air we
breathe. We call this water vapor.
▪ The amount of water vapor in the air is
called “humidity” and varies greatly with
time and location.
▪ Water vapor is an important part of the
water cycle and is a driving force in most
types of weather.
POP QUIZ
▪ 1. ________ is a mixture of gases.
▪ 2. ________ is a blanket of gases that
surrounds a planet.
▪ 3. 78% of our atmosphere on Earth is made
of what gas?
▪ 4. 21% of our atmosphere on Earth is made
of what gas?
▪ 5. Humidity refers to the amount of water
__________ in the air.