Earth's atmosphere. Block diagram showing altitude in kilometres (km) and phenomena observed in Earth's atmosphere. This profile ranges from ground level (at the Ganges Plain and Tibetan Plateau) to an altitude of 180 km. Most of the atmosphere and its weather occur in the first 20 kilometres. The layers are: the troposphere (0-12 km), the stratosphere (12-48 km), the mesosphere (48-80 km), the thermosphere (80-160 km). Phenomena shown include stratus, cumulonimbus, and cirrus clouds in the troposphere, the ozone layer in the stratosphere, noctilucent clouds in the mesosphere, a meteorite trail and aurorae (red and green) in the thermosphere.