But at a ridiculously sparse density. At anything above 10km, it’s not even 1 data source per hundred thousand square km of area at any given time.

Countries the size of Poland go without for at least a decent chunk of the 8760 hours in a year.

Satellites only look at the surface (and maybe clouds).

Weather balloons are extremely sparce.

I see this pretty often here unfortunately. Very confidently wrong statements from people who aren’t actual experts. For historical reasons there’s a sort of guise of expert on HN that can be abused.

This is how the tech nerds operate. Read a wikipedia paragraph, and become expert.