It has received increasing attention in the last several decades because of the dramatic impact humans are having on the chemical reactions there. In fact, since the onset of industrialization around 1800, people have treated the atmosphere as an infinite waste dump. If we were to go outside and stick a barometer and a thermometer onto a weather balloon and then send it up into the sky for 100km or so, we would notice very distinct changes along the way because the atmosphere is structured into several zones. Pressure declines pretty much linearly with height, because there is less atmospheric mass. Although it may not feel like a lot, at the earth s surface, we are experiencing the mass of the entire earths atmosphere that is held in place by the force of gravity.
Temperature is warmest at the earth s surface where land absorbs incoming light and reradiates heat.
This zone is called the troposphere . Eventually, at about 10km, the temperature would bottom out below -60 degrees C. and wold again start rising for about the next 40km through a zone called the stratosphere . The reason why temperature increases in the stratosphere is because O3 molecules absorb incoming uv radiation from the sun. The troposphere and stratosphere are where most of the important reactions occur that are relevant to life on earth. So at this point we can let go of our balloon.