CK-12 Foundation
Ck 12: Fifth Grade Science: Earth Science: Weather and Water in the Atmosphere
[Free Registration/Login may be required to access all resource tools.] Discusses what causes weather, what humidity is and its role in the weather, how clouds are classified, and types of precipitation and how they form.
University Corporation for Atmospheric Research
Ucar: Clouds Images
Photos of various types of clouds and diagrams to help you understand clouds.
Iowa State University
Iowa State University: Cloud Pictures
This is a great site from the Iowa State University. This page is a collection of cloud pictures. You view the picture and then click on the text to see what the author thinks the cloud looks like. You can classify the clouds yourself.
Geography 4 kids
Geography4 kids.com: Many Cloud Types
A brief overview of the four most common types of clouds with mention of a few lesser known types.
Science Struck
Science Struck: Nimbus Clouds: Facts
Explains how clouds are classified and the characteristics of nimbus clouds.