Sunday, July 30, 2017


Noctilucent Clouds (NLC) over Letterkenny - 2017 July 18

Around 12:00 am, few faint filaments of the night shining clouds (Noctilucent clouds / NLC) appeared in the sky towards the direction of setting sun on 2017 July 18. The sun had already an inclination of approximately -12 degrees marking the nautical dusk and astronomical dawn. As the clouds slowly swept towards the darker direction and disappeared in the next 1 and half hours, another band of brilliant white NLCs appeared from the horizon in the direction of the brightest sky (the second half of the video). By this time, the sun was beyond -13 degree inclination clearly marking the astronomical twilight. The time-lapse is created from 1479 individual snaps; the shutter speed is adjusted by a couple of seconds more a few times during this capture sequence to compensate the darkening sky. In the last few 100 clicks, I had to turn the camera a little bit towards the North East to frame the NLCs that appeared in the distant horizon. The big dipper can be seen sweeping towards the right from the top left corner.

Saturday, July 01, 2017

Noctilucent clouds spotted from Letterkenny on 2017 July 01 at 02:15 am

For the first time in my life, I identified the NLC (Noctilucent clounds) at around 02:15 am local time in Letterkenny on 1st July 2017. I drove towards the outskirts of the town to get a better view free from any obstruction from the city lights and got these beautiful pictures. Night clouds or noctilucent clouds are tenuous cloud-like phenomena in the upper atmosphere. They are the highest clouds in Earth's atmosphere, located in the mesosphere at altitudes of around 76 to 85 kilometres. These clouds can be observed only during local summer months and when the Sun is below the horizon for the observer, but while the clouds are still in sunlight. Noctilucent roughly means night shining in Latin.

Noctilucent clouds are not fully understood and are a recently discovered meteorological phenomenon. For example, during my school days these clouds were not even mentioned among the cloud's classifications in the science text books, and I don't think that they made into the curriculum even now. It may be because of the fact that this recent discovery is not well understood and is only visible in the summer months at latitudes between 50° and 70° north and south of the equator. These are becoming increasingly visible, and at times, man made rockets also causes these clouds to appear, and at times due to meteor breaking up in the atmosphere and from it's debris.

You can read more about these clouds in Wikipedia here