Midsummer skies are not ideal for stargazing as it doesn’t get dark until late in the UK. But this is the time of year when spectacular clouds can appear at the edge of space.
These electric-blue wisps show up during midsummer in the northern part of the sky. They are usually more common in northern latitudes, but bright displays can be seen in the far south of the UK. Here is SPA member Richard Fleet’s beautiful video taken in 2013 from Wiltshire (click on the title below to view it full size).
You can also view Richard’s talk to an SPA meeting about NLC and other night glows.
The phenomenon is known as noctilucent (night-shining) or mesopheric clouds. They form more than 80 km up and have been seen from the International Space Station too. It is not difficult to tell the difference between noctilucent clouds (NLC) and ordinary weather clouds because the former can be seen shimmering brightly long after the Sun has set below the horizon.
Why they occur is still not fully understood, but their beauty may be due to a serious cause in the form of increased pollution or climate change. Other suggestions include meteoric dust or rocket exhaust. Latest research suggests that changes in the make-up of atmospheric gas or its temperature has caused the clouds to become brighter in recent years.
The SPA Aurora Section welcomes reports of these interesting atmospheric spectacles and have a guide on how to view them. They also make a very photogenic subject, so do try to capture them with your camera if you can keep it steady, e.g. with a tripod.