0 relating to the ionosphere (= the part of the earth's atmosphere from about 60 kilometres to about 1,000 kilometres above the surface):
The ability to forecast ionospheric conditions is related to solar activity.
The fade-out of radio communications was caused by ionospheric activity.
We can complete it step by step however long the road is and it can't be completed however short the road is if you don't even mark your footprint.