What does cdg mean in a typhoon?

CDG: Is it cold? Darkness? Gray (cold dark gray) is a color code (IR-BD) obtained by enhancing the color of infrared cloud image (IR) when analyzing the intensity of tropical cyclone by using dvorak satellite cloud image analysis method. The cloud convection indicated by CDG is strong, and the cloud top temperature is lower than -8 1℃.

If a tropical cyclone has a full circle of CDG in the cloud area around the eye, but the temperature in the eye area is very high (such as OW or WMG in the color code), it means that the intensity of the tropical cyclone is very strong.

Supplement: IR-BD color chart for dvorak satellite cloud image analysis;

WMG? (warm? Medium? Gray, warm gray and medium gray), cloud top temperature is higher than 9℃;

Ow (off? White), cloud top temperature-30 ~ 9℃;

DG (dark? Gray, dark gray), cloud top temperature-41~-31℃;

MG (medium? Gray, medium gray), cloud top temperature-53 ~-42℃;

LG (light? Gray, light gray), cloud top temperature-63 ~-54℃;

Grade B (black), cloud top temperature-69 ~-64℃;

W (white), cloud top temperature-75 ~-70℃;

CMG (cold? Medium? Gray (cold medium gray), cloud top temperature-80 ~-76℃;

CDG (cold? Darkness? Gray, cold dark gray), cloud top temperature below -80℃.