AIM Banner


The atmosphere is divided into different layers that are defined by the temperature and how the temperature changes with altitude. The lowermost layer is called the troposphere. Here temperature generally decreases with height. This is because as you go higher, you're moving farther away from the main heat source - the Earth itself. The troposphere extends from the surface up to about 10-15 km (6-9 miles) in altitude. "Weather" occurs in the troposphere, and this is where most of the clouds that we typically see are.

The layer of the atmosphere just above the troposphere is the stratosphere, which extends up to about 50 km (30 miles). In this layer, which is higher than most planes fly, temperature increases with height. This is because ozone in the stratosphere absorbs sunlight, heating up the air around it. Some people call the stratosphere the "ozone layer" because most of the ozone in the atmosphere is in the stratosphere.

Above the stratosphere is the mesosphere, where temperature again decreases with height. This decrease continues up to about 90 km.

Finally, the highest layer is the thermosphere, where temperature once again increases with height. This is because molecular oxygen in the thermosphere absorbs sunlight.

The upper boundaries of the troposphere, stratosphere and mesosphere are called the tropopause, stratopause, and mesopause, respectively. The "pause" suffix indicates that this is the "top" of the layer, just like a pause in ordinary speech indicates an end to something.

Image showing Earth's atmosphere. Please have someone help you with this.

PBL Navigation

> PBL Scenario
> Layers of the Atmosphere
> What is a Cloud?
> Weather and Climate
> How Clouds Form, Saturation and Nucleation
> Clouds in the Lower Atmosphere
> Clouds in the Upper Atmosphere
> How Does Climate Affect the Atmosphere?
> Glossary

Teacher's Guide

I. AIM Mission Objectives
II. Key Questions for Students
III. Problem-Solving Model
IV. Materials and Procedures


A: Sample Student Activity Sheet
B: Assessment Rubric
C: National Science Education Standards

NASA's Sun-Earth Education Forum Logo

The AIM mission is a part of
NASA's Sun-Earth Connection Education Forum.

Responsible Official: James M. Russell III

Web Curator: Emily M. W. Hill
Emily Hill Designs