Viscosity is the resistance to flow (opposite of fluidity). Viscosity depends on primarily on the composition of the magma, and temperature. Higher SiO2 (silica) content magmas have higher viscosity than lower SiO2 content magmas (viscosity increases with increasing SiO2 concentration in the magma). Lower temperature magmas have higher viscosity than higher temperature magmas (viscosity decreases with increasing temperature of the magma).
Google does not specifically recommend either DirectX or OpenGL for Google Earth. You can configure Google Earth to operate in either DirectX or OpenGL rendering modes.If your system crashes or performs poorly in one mode, Google recommends you switch to the other mode.penGL Overview. OpenGL is a platform-neutral, open API for rendering graphic images. Although the API is different, OpenGL provides Google Earth with the same graphics performance enhancements as DirectX. OpenGL was originally developed by Silicon Graphics Incorporated.
There is a Google AppSpot website that will let you overlay Google Maps (and many others) in Google Earth for Free (You do need have a gmail account and allow the site monitor your usage). http://ge-map-overlays.appspot.com/. share | improve this answer.edited Oct 21 '11 at 21:30. answered Oct 21 '11 at 19:41. couldn't find any official documentation but, my guess is that it has to do with the licensing of the third-party data Google uses for the map tiles. Google Maps is free to use, but Google Earth, in addition to the free version, has a license structure.