This is the second most abundant gas in the air

when fossil fuels are burned they produce

this is the amount of matter in a given space

this is the force exerted on an area

is an instrument that is used to measure air pressure.

this kind of instrument consists of a long tube that is closed at one end and open at the other.

it’s a metal chamber that is sensitive to changes in air pressure.

it is the outermost layer of earth's atmosphere.

it extends from 80 Km above earth''s surface outward into space and has no definite limit

in this layer temperatures reach 1800ºC but molecules of air move fast and are spread apart so they cannot warm up objects.

it begins at 50 Km above the earth's surface and ends at an altitude of 80 km

teamperatures aproach -90ºC in this layer

it contains the ozone layer

there is much more ozone than in the rest of the atmosphere in this layer

it is about 12 KM but it varies from 16 km thick to 9 km thick

the temperature on the top is about -60ºC in this layer