I found some stuff on mammatus I posted last year.
Posted: Mon Jul 19, 2004 4:20 pm
Mammatus clouds gets its name, because of the puch like or baglike sacs that resemble cows udders. MOOOOOOO goes the cow. LOL Mammatus form in sinking air, when precip is carried aloft, is spread out at the top of the anvil, the precip particles composed of water and ice and since air is saturated and is heavier, it sinks. Sinking air warms, and the warming is used in evaporating the precip particles, if more energy is needed, the sinking air will be cooler than the surrounding air, and with relative humidities of 100 percent, you will see mammauts clouds. Mixing, evaporational cooling and virga seem to play a role in mammatus.
Mammatus often form on the underside of cumulonimbus clouds, especially underneath the anvil and seen more often with storms that are severe, but you can see mamatus with non-severe storms too. Mammatus also sometimes they can form underneath altocumulus, altostratus, cirrus, cirrocumulus and stratocumulus clouds. Mammatus usually are an indication the storms are weakening and threat for severe weather has passed, however they are exceptions to the rule, you can sometimes have mammatus on the backside of a thunderstorm, where you might have the storm dropping hail and/or storng winds. Mammatus are not a sign that a tornado is about to form. Mammatus clouds do not produce severe weather.
Source: Notes I have collected over the years.
Mike
