What are these noctilucent clouds? Well, I’m sure you can easily deduce it. That’s right they are ‘night-shining clouds’. And now is the start of the season for them (they only occur in the northern hemisphere between June and August). These simply aren’t your normal clouds though, these are something special.
First of all they are the highest clouds in the atmosphere. They occur in an area called the mesosphere (they’re also called polar mesospheric clouds for this reason). The mesosphere sits atop the stratosphere which itself sits atop the troposphere (which is where all other clouds and weather form). So these things are pretty high up, 75 – 85km up in fact.
So why do these things ‘night-shine’? It’s pretty simple really, they occur so high up that if you were where they were you’d be able to see the Sun. So they simply reflect the sunlight they’re seeing down to us.
The problem is is that not a lot is known or understood about these clouds, how they form and so on. The best thing though is that you can help. There’s a lovely little Facebook community who go out and report and photograph sightings. There’s also a very useful forum if you wish to know more.
So become a citizen scientist for the summer and help us learn more about these peculiar clouds!