Earth science data spans satellites, oceans, the solid earth and water. NASA's EOSDIS is the main gateway for Earth observation products, and 38-Cloud provides Landsat 8 scenes with pixel-level cloud masks. Ocean data comes from IMOS (roughly 30TB of measurements), BODC, the Alabama Real-Time Coastal Observing System and NOAA's estuarine monitoring program. Geohazard records include the USGS earthquake archives and the Smithsonian Global Volcano and Eruption Database.
Water and resources are covered by FAO's AQUASTAT, the Global Wind Atlas, the UK Oil and Gas Authority's well, seismic survey and pipeline data, and a US water hardness table. NASA Earthdata downloads need a free Earthdata login. Satellite and ocean products are often HDF5, NetCDF or GeoTIFF with their own processing levels, so read the product guide to see whether values are raw, calibrated or gridded before you combine them.