National Geographic’s online atlas. An interactive tool that allows users to select from a variety of subjects in order to combine different layers to be able to visualize the physical geography across the globe. Layer categories include food, climate and weather, U.S. History, water, earth systems, human populations, environment, energy, animal ranges, culture, economy, and political boundaries. Within these categories, there are layers that relate to the hydrosphere, lithosphere, atmosphere, and biosphere. (en)