Planck spectral exitance vs wavelength — log scale
Blackbody curve
λ
peak
(Wien 2898/T)
MWIR window 3–5 µm
LWIR window 8–12 µm
5–8 µm opaque (H₂O)
Source temperature
Temperature T
900 K
Wien's law: λ
peak
= 2898 / T[K]. Hotter bodies peak at shorter wavelengths and radiate far more total power (∝ T⁴).
Peak λ (Wien)
—
—
Total exitance
—
σT⁴, W/m²
In MWIR 3–5 µm
—
fraction of total
In LWIR 8–12 µm
—
fraction of total
—
The plume peaks in the MWIR; the cool airframe peaks in the LWIR. Same physics decides what the B-21 must hide.