The above image was taken by the GOES-15 (West) satellite at 11AM (PDT) today, Jun 5, 2017. At least that's what NASA would have you believe. But we don't have to take their word for it, we can check for yourself.
Verifying that satellite images are real is done by comparing them against the "ground truth" - i.e. the actual situation on the ground. Here I'm going to focus on the GOES satellites, Particularly GOES-East and GOES-West. The process is:
- Pick a Satellite with the best view of your region
- Find out when it will take full-disk photos
- Pick a day when there's some interesting clouds or contrails in the sky
- At that time go outside and take lots of photos in every direction (over five minutes or so)
- Wait for the full disk photo to be downloaded from the satellite and appear on the web site (about 35 to 40 minutes for GOES images)
- Compare your photos with the satellite image.
- Japan: Himawari-8 (JME), RAMDIS Feeds , JME Feed (11K)
- USA: DSCOVR (L1)
- Europe: Meteosat-10 (11K)
- India: INSAT
- Russia: Elektro-L (11K)
- USA: GOES-West & GOES-East. (Raw West, Raw East)
The latest file should be at the bottom. The filenames are in the date format YYMMDDHHMM then G15 for GOES-15 and I01 for the image type (visible). So 1706051800 is 2017-June-05 1800 UTC. Where 18:00 UTC is the time in UTC, and you will want to convert it to your local time. I use google for this, like:
(Note both times say Monday, UTC might be a day ahead or behind the local date, depending on what time it is)
So, I took lots of images at around 11AM, then waited and download the 1800 UTC image. This is a TIF file, and not all programs can open it, so try different ones. Then you will probably want to increase the brightness if you can.
There's a variety of things you can compare, but probably the simples is the cloud cover - and more specifically the airplane contrails that appear in the image. Here's a closer look at a region of California with some landmarks identified. This is simply a part of the above image.
You can see there's a a few contrails there. Notably there's four that form a trapezoid shape around my location. Here I've color coded them:
If you are lucky you will also be able to get a MODIS image from about the same time. This can be helpful in interpreting what you are seeing, but is not strictly necessary:
Then we just need to compare against the photos. It's best to use a wide angle lens, or if not, you can use the panorama mode on your camera/phone. Ideally you would capture a high resolution 360 degree image of the sky.
This is one I took, unfortunately a few minutes early:
This makes the contrails look curved, but they are actually straight
Here's the view looking west at 17:56. I've indicated the blue and yellow contrails:
The images being a few minutes off means the contrails have moved. This shows the importance of getting the images as close as possible to the actual imaging time of the satellite.
[To be continued]
Original TIF file: https://www.metabunk.org/sk/1706051800G15I01.tif
High Resolution JPG: https://www.metabunk.org/sk/1706051800G15I01.jpg