You kind of never been military buff eh? Even as a child? Who were your parents Beatniks? Plenty airplanes during WW2 were painted light blue at the bottom. The top cammouflage is according operation theater. That's why plenty planes in carrier duty were blue. If you see them from the top... they are likely parked or you at least have the advantage position. Sky not to be considered. Silver airplanes glare in the sun, so you aim for the glare even if shape not recognized. Today anti air weaponry is heat seeking and visual is less of an issue to be considered. Missiles are "Fire and Forget". Known Secret: Military Airplanes "Squack". That is... sending a signal that will be identified by all allied airplanes to avoid destruction by "friendly fire" in a war environment. True Story: Mediterranean Sea in the 90's CTF 60 Carrier Group is tracking large airplane in the sky not Squacking, "commercial planes also produce signals identifying themselves as civilian commercial planes." PLANE GOT TOO CLOSE. Was forced to be identified... It was... "Air Force 2". Easy on the poison you taking my Friend... is making you overthink things. I knew that by the time I was 8 and started building models.

They fly low. By the time you see the belly, it's too late.

Perhaps reflective blue on the bottom half , and dull camofluage on the top half ?

And it's not raining or snowing!

And put an exhaust on the noisy things! Blue only works when you are looking up.