[hatmatrix]

C and C++ are definitely the competitors to Fortran; not Chapel or Python. In the life sciences, large amounts of Fortran code has been rewritten in C/C++. But they have orders of magnitude more funding than climate science and teams of professional programmers to maintain the code.

Fortran is a domain-specific language for scientists, and excels at array arithmetic (for graph-based problems though, maybe look elsewhere). Even badly-written code can run reasonably fast, which is not the same for C/C++. There is also the decades of concerted hardware and compiler optimizations that make Fortran hard to beat on HPC systems.

It's not as readable as Python, but it's more readable than C/C++ written by a professional programmer.

[cozzyd]

There's a saying among physicists that you can write Fortran in any language.

[hatmatrix]

I've seen it with my own eyes. It's not pretty, but usually works.