How do scientists separate the layers of the atmosphere

Well, there are five layers in the Earth's Atmosphere:

(In order from the inside out)

1) Troposphere
- This is where weather occurs.

2) Stratosphere
- This is the layer where jets fly, this is where jet-streams are found

3) Mesosphere
- Meso ("Middle") named because it is in the middle. This is where meteros burn up in the atmosphere.

4) Thermosphere
- Thermo ("Heat") Names because it is the hottest layer in the atmosphere. This is where the aurora borealis, or northern lights occur.

5) Exosphere
- Exo ("Outer") This is the outmost layer and it is where the atmosphere merges with outer space.

Humans can affect weathering and erosion in several ways.  humans cause  increases in acid rain and pollution, which increase the amount of  weathering  agents in the air and water, and then on land.for an easy answer: 1) acid rain2) pollution