What does tracer mean or why do the flak lines curve? I could try to look this up myself, but it probably would confuse me more. I don't really understand weapon systems and I feel like somebody here could just answer it easily in a simple way.
"Tracer" is the type of bullets or projectiles, that are illuminated as soon as they are fired.
This is very useful to distinguish and "trace" other projectiles especially in the middle of the night.
Flak lines don't curve. Well, depending on the wind strength, it could. But most of the time, it doesn't.
Those are just some plane trail marks, due to their hard banking maneuvers to avoid the flaks.
"Flaks" by the way...erh.
Just imagine an ordinary bullet.
Then make it bigger. At the size of a chair.
Then put smaller metal balls or smaller things inside.
And when it is fired, the bullet will explode in the air to release all of the smaller things to penetrate the flying planes or whatsoever up in the sky.