Colour state other than clouds or low visibility (e.g. ice or other obstructions) then the word BLACK is written in full and placed immediately before the actual colour state (e.g. BLACKWHT). The colour state may be appended to a METAR report. A short period forecast called a "TREND" which covers the following two hours from the observation may also be added, often with reference to the colour state. The following criteria are used to determine the colour state: Colour state Colour states is a system used for quickly showing meteorological conditions. Meteorological colour states are determined by the relevant worst condition from
Expert Simon and Kevin Gilmartin proposed a model of learning in chess called MAPP (Memory-Aided Pattern Recognizer). Based on simulations, they estimated that about 50,000 chunks (units of memory) are necessary to become an expert, and hence the many years needed to reach this level. More recently, the CHREST model (Chunk Hierarchy and REtrieval STructures) has simulated in detail a number of phenomena in chess expertise (eye movements, performance in a variety of memory tasks, development from novice to expert) and in other domains. An important feature of expert performance seems to be the way in which experts are able to