Friday, June 30, 2017
The Cumulonimbus Incus
In my neck of the woods the weather has been unsettled the last few days and while leaving the mall on Thursday, June 29th a huge cumulonimbus incus cloud was visible to the East.
A cumulonimbus incus (Latin incus, "anvil") also known as an anvil cloud is a cumulonimbus cloud which has reached the level of stratospheric stability and has formed the characteristic flat, anvil-top shape. It signifies the thunderstorm in its mature stage, succeeding the cumulonimbus calvus stage.
A cumulonimbus incus is a mature thunderstorm cloud generating many dangerous elements.
Lightning; this storm cloud is capable of producing bursts of cloud to ground lightning.
Hail; hailstones may fall from this cloud if it's a highly unstable environment (which favors a more vigorous storm updraft).
Heavy rain; this cloud may drop several inches of rain in a short amount of time. This can cause flash flooding
Strong wind; gale-force winds from a downburst may occur under this cloud.
Tornadoes; in severe cases (most commonly with supercells), it can produce tornadoes.
Cumulonimbus clouds can be powerful. If the correct atmospheric conditions are met, they can grow into a supercell storm. This cloud may be a single-cell thunderstorm or one cell in a multicellular thunderstorm. They are capable of producing severe storm conditions for a short amount of time.
Thunderstorms are formed of what are known as cumulonimbus clouds which grow from the billowy cumulus clouds. If the sun heats up the ground thermals form and the warm air and it rises, pushing up the clouds. They keep growing upwards and then reach what is known as the tropopause which is the part of the atmosphere between the troposphere which is the bit nearest to the ground and the stratosphere which is the next layer up.
What you get here is known as an inversion which is where you get cold air sitting over warm air. What everyone is used to is the warm air rising and therefore being above the cold air. This doesn't happen in the stratosphere because it gets colder and colder as you go up. This means that the clouds can't go any farther and it spreads out along the top and it's very flat.
Fortunately there wasn't any severe weather associated with this cloud.