Colour centre in humans as an area specialized for colour vision. V2, also called the prestriate cortex, is believed to have a small role in colour processing by projecting signals from V1 to the V4-complex. Whether or not colour selective cells are present in V2 is still being investigated. Some optical imaging studies have found small clusters of red-green colour selective cells in V1 and V2, but not any blue-yellow colour selective cells. Other studies have shown that V2 is activated by colour stimuli, but not colour after images.[8] V4 also has feedback on V2, suggesting that there is a defined network
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