Michiel, Pagman, and other lovers of classic jets, here is a 48 year-old DC-8, that you are likely to see in CA and FL.
According to NASA's website "NASA operates a highly modified Douglas DC-8 jetliner as a flying science laboratory. The aircraft, based at the NASA Armstrong Flight Research Center facility in Palmdale, California, is used to collect data for experiments in support of projects serving the world's scientific community. Federal, state, academic and foreign investigators are among those who use NASA’s DC-8."
The crew and jet are spending about 30 days here in Florida to study atmospheric conditions among other things.
A friend of mine who works at the airport has some "wicked" close-up shots of this DC-8 like these: