Atmosphere Study Guide

thin layer or envelope of gases that surrounds Earth; traps energy from the sun which allows water to be a liquid; plants and animals need the gases to survive

most abundant gas in the atmosphere

a form of oxygen with three oxygen atoms in each molecule

water vapor
water in the form of a gas; it makes air not dry

mass, density, and pressure
three properties of air

aneroid barometer
instrument used to measure air pressure without liquid

created by smoke and fog

lowest and shallowest layer of the atmosphere; layer where weather occurs and people live

contains ozone and protects living things from ultraviolet radiation from the sun

divided into two layers, the ionosphere and the exosphere; outermost layer of the Earth’s atmosphere; has no definite outer limit

layer of atmosphere that protects Earth’s surface from being hit by most meteroids

harmful substances in the air, water, or soil

burning fossil fuels
creates most most air pollution

photochemical smog
sunlight on pollutants causes a brownish mixture of ozone and other pollutants

elevation, or the distance above sea level; air pressure decreases as altitude increases (air becomes thinner)

air pressure
weight of a column of air pushing down on an area; doesn’t crush us because air pushes in all directions; units measured in millibars and inches of mercury

air is about 78% nitrogen and 21% oxygen
at sea level; at top of mountains; in cities and surrounding suburbs

troposphere, stratosphere, mesophere, thermosphere
four main layers in our atmosphere from Earth to space; divided by scientists based on changes in temperature

condition of the Earth’s atmosphere at a particular time and place

acid rain
contains more acid than normal; rain is naturally slightly acidic