Cloud the bottom of the hierarchy. Clouds in the troposphere assume five physical forms based on structure and process of formation. These forms are commonly used for the purpose of satellite analysis. They are given below in approximate ascending order of instability or convective activity. "Non-convective" stratiform clouds appear in "stable" airmass conditions and, in general, have flat sheet-like structures that can form at any altitude in the troposphere. The stratiform group is divided by altitude range into the genera cirrostratus (high-level), altostratus (mid-level), stratus (low-level), and nimbostratus (multi-level). Fog is commonly considered a surface-based cloud layer. The fog may form
And/or way to indicate inclusive or. Kenneth Adams, lecturer at Pennsylvania Law School and Alan Kaye, professor of linguistics at California State University, wrote, "It does, after all, have a specific meaning—X and/or Y means X or Y or both." The legal usage authority Bryan A. Garner stated that use of the term is particularly harmful in legal writing because a bad-faith reader of a contract can pick whichever suits them, the "and" or the "or." Courts called on to interpret it have applied a wide variety of standards, with little agreement. And/or And/or (also and or) is a grammatical conjunction