Homepage of NLC time-lapse movies

Since the summer 2004 we run a digital photo camera (Canon PowerShot G5) from the top floor window of the Arrhenius Laboratory at the University Campus in Frescati, Stockholm. The camera operates in the interval time shooting mode, taking every night hundreds of pictures of the twilight sky at the rate of 1 to 2 pictures per minute. Time-lapse movies made of these picture series for selected nights may be downloaded as .avi-files further below.

NLC occurance and brightness results obtained from these photographic observations for the last NLC-season (summer 2009) are summarised in the plot below.

The brightness and the extent of NLCs are represented here on the scale from 0 to 4 according to the following (obviously subjective) criteria: 0 = no NLC, 1 = local and weak, 2 = weak but extensive, 3 = strong but local, and 4 = strong and extensive.

To account for the visibility, tropospheric cloudiness and the presence/absence of data we use a scale from 0 to 1 in the following steps: 0 = clear skies, 0.25 = cloud patches, 0.5 = cloudy but with some openings, 0.75 = complete cloud cover, and 1 = no data. With this kind of scaling we hope it should be fairly obvious from the plot above that we are missing the data for a number of nights around day no 168 or so (June 16-18) and the reason that we do not detect NLCs around the days no 210-220 is not necessarily that they were not there, but the weather was bad and we simply cannot tell!

Contact Jacek Stegman for any further details.