Convection

Table describing some of the most widely used RGB products, with a sample image for the convection RGB

Description: This RGB can identify important microphysical trends in convection, including small ice particles that mark intense updrafts and are potential indicators of imminent severe weather.

Coverage: Daytime only

Channels: MSG 0.6-µm VIS; 1.6-µm NIR; 3.9-µm IR; 6.2-µm WV; 7.3-µm WV; 10.8-µm IR

Color scheme:

  • The background is blue/magenta
  • High-level, thick, ice clouds, including convective cumulonimbus clouds, are red
  • Yellow is usually indicative of small particles within convective cloud tops

Advantages: Compared to many satellite images, this RGB shows the most intense cells, which can help distinguish new convection from dissipating convective activity.

Limitations:

  • Daytime only
  • Not effective at observing or discriminating types of weather other than convection
  • Yellow does not necessarily mean small ice particles; it can also mean very cold cloud tops composed of large ice particles.

Link:

MSG Convection RGB of Hurricane Isabel, June 2006
Click to play animation.

Loop: In this RGB animation of Hurricane Isabel, the reds and oranges show cloud tops composed of fairly large particles. The yellow suggests very small ice particles at high altitudes, which are indicative of intense updrafts.


MSG Severe Weather RGB, South of France & Italy  20 May 2003 1330 UTC

Example: This RGB over southern France and Italy shows strong convection in yellow, an indicator of potential severe weather. Here again, the yellow areas indicate cells with extremely small ice particles at cloud top, suggesting intense updrafts and potential severe weather. The more reddish regions indicate older or more benign convection.


Exercise:

MSG Convection RGB 27 Oct 2004 1300

In this convection RGB over South Africa, three of the five circled areas could be associated with severe weather? The other two are not. (Choose those that apply.)

The correct answers are A, B, and C.

The yellow in these areas usually indicates small particles within convective cloud tops that are associated with strong updrafts. Strong updrafts often indicate the potential for severe thunderstorm conditions. The red areas are usually seen with non-severe convection and other cloud types.