Time-lapse photography of clouds and other phenomena in the sky

My first timelapse of the night sky above La Palma, Canarias. Captured from a view point east of the local observatory, from Mirador de los Andenes (N 28°45.66717', W 17°52.04257'), southward view (center of the frame), width of the frame about 150°. Disadvantage of this location was relatively heavy traffic on the nearby road as well as at the viewpoint itself throughout the night, resulting in the necessity to clone out the nearest surroundings illuminated by the passing or parking cars. A big advantage of La Palma (as compared to the other Canary Islands) is the total absence of air traffic above the island, at least in the night, therefore all the bright lines in the timelapse are either satellites (always in several consecutive frames), or bright meteors, aka bolides (always in one frame only). Due to the low latitude of the island, most of the passing satellites disappear later in the night in the Earth's shadow - thus the low-earth orbit (LEO) satellites are visible in the early evening and early morning only, and just the higher-orbit satellites can be seen during the entire night, slowly drifting across the sky. There are several meteors or bolides captured in this sequence, with the brightest ones being these two: 22:57 UTC and 23:27 UTC (this second bolide leaves a dusty trail behind, persisting for almost 20 minutes, see this short loop). The sky wasn't quite clear on this night, thus the haze illuminated by orange city lights spreads higher above the horizon. In the early morning, the crescent Moon illuminates the sky and the island. The exposure and ISO of this timelapse series (as well as of the next one) during sunset, dusk, dawn and sunrise, was controlled manually, and both series were processed with LRTimelapse (which is now my prime processing tool).

My second sunset-to-sunrise timelapse of the night sky above La Palma, in this case nicely variegated by airglow (nightglow). Taken from a saddle near Pico de la Cruz (N 28°45.38462', W 17°51.36545'), at ~ 2300 m a.s.l., about 100 m from the rim road (and from a nearby small unpaved parking lot). Approx. southward view (azimuth of center of the frame is about 200°), width of the frame about 150°.

The sky was crystal clear this night, with just a weak haze low above the horizon. Shortly after sunset and just before sunrise, there is a very nice, prominent shadow of the Earth in the sky, including the "Belt of Venus". As it gets dark, at the right side of the frame, a weaker Zodiacal light can be seen for a while. Regarding the visibility of satellites throughout the night, see my comments above.

The most interesting feature of the night was this thin reddish beltlow above the horizon, which appeared as the sky got dark, and was drifting quickly to the south. This thin belt was most likely a wave or bore (?) in the red airglow, emitted by chemiluminescence of hydroxyl radicals, OH* at about 85-90 km levels, near the mesopause. To exclude other possible explanations such as a band of thin clouds or dust, satellite data and atmospheric sounding can be utilized, as shown next. Should the reddish belt be a band of thin clouds or dust, it should appear in these Metop-C RGB images (detail or large image), taken when the belt was still visible in the timelapse, or in this Meteosat RGB NM loop - however nothing corresponding to the feature can be found in these. Taking into account  the wind profile (see this midnight Tenerife sounding), southward propagation of the band, and the altitude of the site from which the timelapse was taken, the cloud or dust band would have to be somewhere between 2.5 - 3 km, and thus should be visible even before dusk - which is not the case. The only feature in satellite imagery that resembles the reddish belt by its shape and location, is the feature indicated in this Metop-C IR image by arrows; however, from the MSG IR loop (strongly enhanced IR10.8 band) it is obvious that this feature is stationary, thus it is a sea-surface temperature anomaly. Finally, there is one more argument supporting the airglow nature of the reddish band: should it be a band of clouds haze or dust, the stars behind the band should fade or get blurred behind the band, which is not the case. The SNPP and NOAA-20 satellites with their Day/Night Band (DNB) were of no use in this case, as they passed above the region later after midnight, when the band was already gone. One question remains - what was the mechanism which triggered the wave or bore? Was it the deformation zone near the tropopause, which can be seen north-west of the islands in this MSG WV6.2 loop (the red line indicates very roughly the location and orientation of the reddish band), or some other process in the upper mesosphere, near the mesopause?

Later in the night, part of the sky becomes greenish - a manifestation of green airglow, emitted by atoms of oxygen at about the 90 - 100 km levels. Also, left of the Milky Way (in the smaller image left approx. above the center of the frame) we can faintly see a weak "Gegenschein". Near the end of the night, just before dawn, several dim waves propagating from the bottom left to upper right corners of the frame can be seen - these are atmospheric gravity waves generated by convective storms above northwest Africa.

Six timelapse series of clouds above central parts of the La Palma island, forming famous "cascades of clouds", or "waterfalls of clouds". During the most typical weather pattern in the area, the Azores pressure height, the prevailing winds above Canary islands are from north-east or east, pushing the clouds against the eastern slopes of the island. The Cumbre Nueva ridge in the central parts of the island, reaching about 1400 m, squeezed between the highest parts of the island in the north (Caldera de Taburiente, ~ 2000 to 2426 meters a.s.l.) and volcano ridge at the south (Cumbre Vieja, ~ 1800 to 1947 m a.s.l), poses a natural "gap", through which the clouds can push through westwards, where they dissolve in the warmer and dryer air. See this scheme of the process, and the same Sentinel 2A image in its full 10 m resolution. The process is best shown in the first part of the movie, taken from Pico de Nambroque (1922 m), northward view.