The τ ≈ 1 sweet spot for emission to space
A cartoon of why emission to space, per unit height, peaks near optical depth τ ≈ 1.
Gallery
Figures I’ve made for teaching, each with the code that draws it. Everything here is in the public domain under CC0 1.0, so use and adapt it however you like, with no need to ask or to credit me. Where a figure redraws someone else’s, its page credits the original; please keep that credit when you reuse the figure.