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HPWREN News

February 22, 2005

Time Lapse Animations from HPWREN Cameras show Interesting Cloud and Fog Formations

The recent rains in San Diego County were an opportunity to observe interesting cloud and fog formations. An example is the camera installation described in http://hpwren.ucsd.edu/news/041221.html. This IQeye3 camera uses a monochrome imager and does not have the cyan filter that "normal" cameras have to keep them from near-infrared sensitivity. In addition, the camera has a 900 nanometer bandpass filter in front of its lens. Hence the imager only sees around 900 nanometer, which is near-infrared and invisible to humans. When looking through the lens filter of the camera, it appears totally dark to the human eye. In the case of blue sky, the sky looks almost black, due to the lack of heat. The clouds diffuse the sunlight, and hence appear white. Live green vegetation appears white, as it reflects some infrared. Dead or dying vegetation is far less reflective in that part of the light spectrum.

Clouds above Ramona This December 30, 2004 image shows a cloud and fog view, pointed approximately eastward from above the Dos Picos County Park at the west end of Ramona. Availability of an about 16 megabyte animation is described in this article.


Various time lapse animations have been created from imagery, available at http://hpwren.ucsd.edu/Animations/. These files are usually large and require significant bandwidth and patience to download. It is recommended to save the files onto the local computer and run them locally, rather than across the network. Most of the files are in DVD-compatible MPEG2 format for NTSC, with a four megabytes-per-second variable rate that can burst to seven megabytes-per-second.

  • dp-20041230.mpg is from December 30, 2004, and shows interesting fog and clouds. It is about 16 megabytes (MB) in size. A full 1288x968 pixel resolution AVI file is available at dp-20041230.avi. Its size is about 225MB and requires a fast computer to run on.
  • dp-20050213.mpg, is almost 20MB in size, from February 13, 2005 also shows nice clouds in front of a dramatically dark sky.
  • dp-20050219.mpg (~61MB) and dp-20050220.mpg (~132MB) show time lapse animations from the recent rain falls on February 19 and February 20, 2005.
  • dp-20050223.mpg (~82MB) from February 23, 2005 and dp-20050224.mpg (~81MB) from February 23, 2005 show a mostly lesser cloud cover with a rainbow and a moon rising towards the end.


Rainfall on, among other days, February 20, 2005 shows a rain squall moving through, which looks very dynamic in the described time lapse animations.
Rain above San
Diego County


Other pointers at http://hpwren.ucsd.edu/Animations/ show videos from various locations and times, several in time-lapse format.


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