Equation 11 · Part 1 · How Planetary Science and Exploration Actually Work
Symbol τ
What this part means
τ is a part of this expression. Its role is fixed by the surrounding article and by the operations shown in the formula.
Its job in the formula
τ is a part of this expression. Its role is fixed by the surrounding article and by the operations shown in the formula.
Full expression→Symbol τ→Article meaning
The passage around this formula
where is the incident spectrum, the wavelength-dependent optical depth, n(z) the number density of an absorbing species at altitude z , and its absorption cross-section, which itself depends on temperature and pressure. The instrument records I() ; the abundance profile n(z) is recovered by inverting this relation against a model atmosphere, which means every composition result carries the assumptions of that model — cloud and haze opacity, temperature structure, and the line-list data used for — bundled in with the raw spectral measurement.
Learn the underlying idea
A function assigns an output to each allowed input. The expression f(x) means “apply f to x”.
Open the illustrated functions: inputs become outputs guide →
See this notation across published equations →
Sources cited in the article section
These citations provide research context; check each source for the exact claim it supports.