Troposphere

The lowest part of the atmosphere from the surface to about 10 km in altitude in mid-latitudes (ranging from 9 km in high latitudes to 16 km in the tropics on average) where clouds and "weather" phenomena occur. In the troposphere temperatures generally decrease with height.

Source: GreenFacts

Layers of the atmosphere:

Source: based on Harcourt School publishers 

Atmosphere - Stratosphere

Fluoride

Climate Change

Ozone

Marine Litter

Climate Change