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Climate change is commonly described in a simple way as a warming of the Earth due to the addition of certain gases into the atmosphere by humans. In truth, the process is complex and requires careful thought. As we mentioned earlier, one must consider changes in weather versus changes in climate. How long does it take to realize changes in climate versus changes in weather? Also, just because the atmosphere at the surface of the Earth is warming, does that mean that the entire atmosphere is warming? In fact it does not. The greenhouse gases allow the atmosphere to radiate energy (infrared light) more efficiently. Because much of that radiation is directed towards the Earth, the surface of the Earth is warmed. But because the upper atmosphere is emitting energy more efficiently toward space, the temperature there is reduced. Thus climate change is manifested very differently in the upper versus lower atmosphere.

We should also be careful to remember that not only might temperature be changing, the amount of water in the atmosphere is also changing. Increased temperatures at the Earth's surface lead to increases in evaporation of water. And although much of the water vapor in the atmosphere comes from the oceans, water vapor can also be made in the atmosphere from another gas called methane. Adding methane through pollution or biologic processes eventually leads to more water in the upper atmosphere.

For more information:

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

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

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