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
Immediate or cancel Immediate or cancel An immediate or cancel (IOC) order, also known as an "accept order", is a finance term used in investment banking or securities transactions that refers "an order to buy or sell a stock that must be executed immediately". In case the entire order is not available at that moment for purchase a partial fulfillment is possible, but any portion of an IOC order that cannot be filled immediately is cancelled, eliminating the need for manual cancellation. This "partial fulfillment" aspect is what differentiates IOC orders from all or none (AON) and fill or kill (FOK) orders. It