I was floating around the Internet yesterday and found a wonderful cache of photographs currently held by the National Oceanic and Atmospheric Administration. These pictures, which are now part of the public domain, can be found at NOAA Photo Library. According to the website, you are allowed to use these pictures, as long as you give credit back to NOAA or their affiliates. (Check About the Images for more information.)
So, what sort of pictures do they have? How about these?
A Coral Reef in the Florida Keys
Photo credit: Florida Keys National Marine Sanctuary
A Snowflake Photograph taken by Wilson "Snowflake" Bentley
Photo credit: NOAA
An Intense Cloud to Ground Lightning Strike
Photo credit: NOAA Photo Library, NOAA Central Library; OAR/ERL/National Severe Storms Laboratory (NSSL)