7 Rare clouds types | Amazing Weather

Most of us see clouds every day, but only very occasionally will you be lucky enough to spot one of these 7 particularly rare types – some of which can only be seen in very specific circumstances or locations.

Noctilucent clouds

One of the rarest and most beautiful of all cloud types. They are found at very high altitudes – up to around 250,000 feet Visible on clear, summers nights between 45 °N and 80°N latitude ,they appear illuminated by a blue or occasionally red or green light. We still do not know much about how they are formed, but they are thought to be made up of ice crystals.

Kelvin-Helmholtz clouds

They can sometimes be seen as far as 60 miles downwind of the mountains that formed them. An extremely rare phenomenon, where clouds form as a billowing wave pattern Occurs when there is a strong vertical shear between two air streams. This causes some winds to blow faster at the upper level, than at the lower level.

Mammatus clouds

Bulge or pouch shaped, they’re usually seen emerging from the anvil at the top of cumulonimbus clouds. Formed by turbulence, they are one of the few clouds that come from sinking, rather than rising air.

Lenticular clouds

Usually formed behind hills or mountains, where the air is stable and winds are blowing from a similar direction. These tall geographic features interrupt the wind, the airflow undulates and condenses into these disc shaped clouds.

Funnel clouds

Cone shaped clouds which extend from the cloud base, but never actually touch the ground. Formed in the same way as a tornado around a small area of intensely low pressure. If a funnel cloud reaches the land it becomes a fully fledged tornado and if the funnel cloud reaches the surface of a body of water, it becomes a waterspout.

Fallstreak Hole clouds

Also known as a hole punch cloud – they form when part of the cloud layer turns to ice crystals which are large enough to fall. Water droplets in the cloud, cooled below 0°C but not yet frozen, will freeze if they find a particle to freeze on to or are cooled to below -40°C. Aircraft can cause this to happen by making the air expand & cool as it passes through the cloud

Arcus cloud

Formed when warm air within a storm cloud is pushed up from the ground by the cold air exiting downwards. Unattached to the storm cloud they are known as roll clouds, but when attached they are called shelf clouds.

Noctilucent Cloud Display over NE England June 2019

noctilucent clouds over durham city Noctilucent Clouds over Durham City, June 17th/18th 2019 by Mike Ridley Photography

Some of you eagle-eyed skywatchers will have noticed a ghostly glow in the sky on the way back from the pub in recent days. Was it real? Was it just an illusion caused by too much Gin? No, what you saw was real and is called ‘Noctilucence’. It is a spectacular display of very high clouds.

Noctilucence is exhibited by clouds that shine at night (Noctilucent means ‘night shining’ in Latin). Noctilucent Clouds exist in the upper atmosphere (Mesosphere), at a height of around 50 miles. They are composed of ice crystals and can only be seen in astronomical twilight. That means they are best seen in the summer months, but they are too faint to be seen in daylight. They require moisture, dust and very cold temperatures (less than -120 degC) to form. The Mesosphere is at it’s coldest in the summer months, so favours their formation.

The clouds shine on summer nights when the sun is below the horizon at ground level, whilst up at 50 miles the noctilucent clouds are still in the sunlight. The whispy clouds seem to glow in this ghostly manner. They are a comparatively recent discovery and are not fully understood, but they seem to be occurring more often and with increasing brightness.

There have been some fantastic photos posted on the internet in the last week or so, but the best I have seen relevant to us is from Mike Ridley who took this superb composite photo over Durham City from Whinney Hill on 17th/18th June 2019.

Here’s Mike’s link.

Mike Ridley Photography

noctilucent clouds by mike ridley photography Noctilucent Clouds over Durham City, June 17th/18th 2019 by Mike Ridley Photography

Funnel Cloud seen over North East England – 28th May 2019

The report above appeared in the Northern Echo newspaper on 29th May 2019.

The axis of funnel clouds may be vertical, inclined (as seen here), or sometimes long and sinuous.  In the UK it is usually tens of metres in diamater (not huge). It is much rarer for funnel clouds to touch the ground and that is when they become tornadoes, but it does happen occasionally. Most UK tornado reports come from The Midlands, Central, Southern and South East England and East Anglia. Our very own Tornado Alley!

If you see a funnel cloud or suspected tornado, you should report it to TORRO (Tornado and Storm Research Organisation). They catalog such stuff and produce stats and mapping.

There are 40 tornadoes per year recorded on average in the UK. England has the highest reported incidence of tornadoes per square mile in the World. That usually surprises a few people, but it’s true!

The longest ground track by a tornado in the UK was in May 1950, when a tornado traveled 107km from Buckinghamshire to Cambridgeshire.

Ex-Hurricane Ophelia brings red gloom to Durham

“Southern Ireland was battered by gales, but the strange weather that hit the british mainland was unlike anything i’ve ever experienced. At 2pm in the afternoon, the sky had a strange orange hue, and it was dark – REALLY dark. The streetlights were on and cars were driving with full headlights. It was almost completely still, but a smoky smell hung in the air. This was afterwards attributed to a combination of forest fires over the Iberian Peninsula and Saharan dust, all dragged North on the Eastern side of the depression centre. Within 90 minutes the sun was out and it was a different world.” – Dave O’Hara

A bright red sun glows in the sky over Durham, October 16 2017. It was the 30th anniversary of the Great Storm of 1987. The sun had an eerie red cast because southerly winds ahead of an ex-hurricane Ophelia had drawn air all the way from the Iberian peninsula, where forest fires had been raging.

The photo above was taken in Gilesgate in mid-afternoon, but it was so dark that street lights came on automatically and drivers had to use their headlights to see. There was a strong smell of burning in the air. All birds had fallen silent, believing night was upon them.

A satellite picture clearly shows the red dust and smoke embedded into the weather front approaching the UK.

The month had 3 new daily records in the Central England Temperature record. 17.2, 16.4 and 14.9C on the 14th, 16th and 25th respectively. The maximum temperature at Gilesgate was 19.8 degC on the 13th of the month, with the minimum of 2.8 degC on the morning of 30th resulting in the first ‘car windscreen scrape’ of the Autumn.

Met Office : Ex-Hurricane Ophelia 16 October 2017

Nacreous Clouds over Durham, Feb 2016

A fantastic display of nacreous (mother of pearl) clouds occured across NE England in February 2016. These photos were taken above Durham Cathedral and Castle at about 7:15am.

Nacreous Clouds are quite rare. They can glow very brightly due to iridescence and are much higher than other tropospheric clouds, a height of 15-30km above the ground is typical. They are caused by wave-like motion of air, normally due to the proximity of mountain ranges. Best viewing is just before dawn and just after sunset.

Shelf Cloud over Durham, July 2015

This incredible Shelf Cloud, looking like an alien spacecraft from the film “Independence Day” came in over Durham in July 2015. Although it looked very threatening, on this occasion not much rain fell from it. It’s the best example I’ve seen of a Shelf Cloud in the UK.

On 1st July 2015, the temperature hit 30 degC in Durham, being only the 30th such occasion since 1850 to reach the mark. The actual max was 30.2 degC. It was a very hot sultry day, which quickly degenerated into thunderstorms with rain and hail.

Met Office : Heatwave 1st July 2015

Here’s a video from mid-afternoon

A shelf cloud is a low, horizontal wedge-shaped cloud, associated with a thunderstorm gust front (or occasionally with a cold front, even in the absence of thunderstorms). A rising cloud motion often can be seen in the leading part of the shelf cloud, while the underside often appears turbulent, boiling, and wind-torn.

Here’s a dramatic lightning strike in Ferryhill, the same day