A March evening in 2016 in Minneapolis, most of the snow was gone and the city lights can (surprisingly) look beautiful by way of contrast against the sunsets.
It’s February 28th and as March melts in to the weather scene I have summer and Cumulonimbus on my mind. I miss hot sweltering weather full of billowing clouds and those ominous shelves of gray that rumble in from the west at the end of an afternoon. Especially do I miss the more active and continuous type of summer weather we used to have circa 1999-2003. Storms roared in full of power and exited just as quickly leaving the day humid, hothouse and full of sunshine bouncing off green things, like a jungle.
An airliner nearby to MSP airport with a Cumulonimbus backdrop
A bigger view of the same storm where you can see the cumulus congestus phase of the cloud on the right, which is more crisply defined. The larger cloud on the left is forming the more fibrous and diffuse incus phase in the early evening.
-A Cumulonimbus cloud shows some instability in the atmosphere and has several growth phases, each with their own moniker:
Cumulus Humilis – Humilis is Latin for humble or low and Cumulus means pile or heap, so these could be called heaps of humility? Hmm.
Cumulus Congestus – is the phase of cloud growth that follows humilis. Congestus in latin refers to the action of heaping together.
-Once a cloud leaves the congestus phase it’s top (the part I always think looks like a pile of powdered sugar when I am baking) becomes softer and less crisp in appearance as it turns to ice in the Cumulonimbus phase.
-Cumulonimbus are so tall that the tops can reach over 40,000 feet. Most commercial airlines fly at around 28-35,000 feet.
-Lighting can be seen in the heads of Cumulonimbus. The instability and rising air currents in Cumulonimbus create the conditions most favorable to lightning although lightning can be found in other weather conditions.
-As a Cumulonimbus grows and then begins to dissipate it’s top spreads into an anvil or Incus. It can spread to a much larger area than the cloud it came from. This is my favorite part of the end of a storm when the sun is setting and it throws light onto the bubbled undersides of the incus, called mammatus. You will see ethereal circle and tube shapes against the blue sky in bright pinks and oranges as the light is fading.
The end of a June storm looks so dreamy as the extremely diffuse anvil phase catches the setting sun.
You can make out some of the rounded mammatus features on the underside of the anvil.
I am looking forward to another summer full of the majesty of Cumulonimbus. I always think about the sky – no matter where you are or what is going on, it’s always beautiful and always clean. Do you ever just stop, look up, breathe and feel some of the stress fall off your shoulders for just a moment?
Stay positive and keep looking up!