December cold fronts sweeping south across Lake Okeechobee carry moisture to above the Everglades where the warmth of that body transfers to the cold air and makes it rise. This image is of 1/4 of the sky yesterday to my west and over those 'Glades. Building beautifully broad bilious bounty.
This is looking straight West. So, to the right (North) you can see the moist air that is almost always present over Okeechobee rising to the stratosphere. Then, going to the left (South) you can see individual masses of air, getting higher and higher with each mile south they move. Later, last night, the clouds drifted northward in the dark and brought us a 1/2 inch of rain. The temperature here is daytime 82F but the air mass to the North is about 65F. It is the low cold air that strips moisture from the bottom of the Okeechobee cloud and brings it south. It's like an upside-down chimney in operation.