For a decade, however, the Multi-angle Imaging SpectroRadiometer on NASA\'s Terra spacecraft has been watching Earth\'s clouds. Now, Davies and his colleagues have analyzed the device\'s first 10 years of cloud-top height measurements from March 2000 to February 2010. They found that global average cloud height decreased by around 1 percent over the decade, a distance of 100 to 130 feet (30 to 40 meters). Most of the reduction stemmed from fewer clouds forming at very high altitudes.The researchers reported their results in the journal Geophysical Research Letters. The Terra satellite is set to continue collecting data through the rest of this decade, which will help determine whether or not the cloud lowering is a consistent trend.