@ivo Hey there!
It is not clear yet. I’m monitoring an area 2200ft AMSL and always get confused about the altitudes I select from the moving bar...

• What exactly does “surface” mean in this particular case?

• And if the elevation of the terrain in the surrounding area is 3000ft (therefore 5200ft AMSL) are we getting their respective “surface” data?

• But most important, what does it mean if I choose 330ft or 2000ft charts in these particular examples?

• Another similar question could be done when using flight levels...

Thanks in advance for the explanation!