Atmosphere intro!

Earth's modern atmosphere consists mostly of Nitrogen as a diatomic molecule.

78% of the atmosphere is Nitrogen in this diatomic state.

The composition of Earth's atmosphere.

Oxygen in the form of the diatomic molecule O2 is the next most abundant gas in the atmosphere.

Oxygen is 21% of Earth's atmosphere!

Composition of Earth's atmosphere.

Argon is 0.9% of the atmosphere.

Trace gases fill up the rest as well as things like dust, water, and compounds.

Composition of Earth's atmosphere!

We call this: The Weather!

The condition of the atmosphere at a particular time & place!

Things that happen in one part of the atmosphere affect other parts.
The energy for this system is provided by the sun!

The atmosphere is a system!

The amount of mass in a volume.

d=m/v

Density

Amount of matter in an object.

Anything made from atoms has mass!

Mass

Amount of force on a given area!

P=F/A

Pressure

We call this
Air Pressure!

The result of a column of air pressing down on an object!

PSI is used in the USA

Pa is used everywhere else. (The SI unit of pressure.)

Pound Per Square Inch vs
Pascals

A device used to measure Air Pressure!

Barometers!

A device that measured the weight of the air by the amount of mercury being forced up a tube by the pressure from the atmosphere.

Mercury Barometer!

This barometer uses an air-tight chamber that flexes when exposed to different pressures. The flexing causes a needle to move and indicate the pressure.

Aneroid Barometer!

Most weather reports use this unit. A normal sunny day @ sea level is typically 30inHg

Inches of Mercury!

The National Weather Service uses millibars.
1mb = 100Pa

Normal atmospheric is 1013 mb

Millibars

1/1000th of a bar and is the amount of force it takes to move an object weighing a gram, one centimeter, in one second

This is what a Millibar means.

The higher you go--the less air above you!

This means there is less pressure at higher altitudes and vice-versa!

Altitude Affects Air Pressure!