CLOUD ATLAS

The words may sound confusing, but giving a name to your cloud is as easy as knowing its level and its shape. Missing from this classifier are the multi-levelled nimbo- clouds: endless grey nimbostratus (behind) and the majestic thunderstorm cloud cumulonimbus (right).

Nate’s Fab Five

Choosing a favourite cloud is as hard as picking a favourite child, but here are a few stand outs:

MAMMA

Often called mammatus clouds, these are ominous, pendulous lobes that can be found hanging underneath a cumulonimbus in the right circumstances. They often indicate a severe storm cell.

FLUCTUS

An accessory cloud that gets physicists excited. Curled wave formations called Kelvin-helmholtz waves are caused when an airmass interacts with another above it that’s moving at a different speed or in a different direction. Nothing significant weather-wise, but a rare delight to spot.

PILEUS

When a rising airmass is creating a cloud, it can force a layer of air above it to rise, creating a small stratus above the upwelling cumulus, like a cloud with a whimsical hat.

HOMOGENITUS

Clouds created by human activity, like cumulus forming above a smokestack or cirrus left behind a jet in a contrail (ice particles formed in the wake of the jet by a pressure disturbance).

FLAMMAGENITUS

Clouds formed by the heat rising from a fire. The one you’ll hear about most is commonly called pyrocumulonimbus, but its official designation is cumulonimbus flammagenitus. These clouds are incredibly difficult to forecast and can cause widespread havoc with sudden changes of wind direction and lightning.