Question

On a clear day, you use an infrared thermometer to measure a blackbody temperature of 273 K looking towards the horizon and 255 K looking directly upwards. Estimate the longwave emissivity and optical depth of the atmosphere. Noting that and assuming that the slant path optical depth T -> infinity looking towards the horizon.

1 Planck-ε01derm therm

Answer 1

Given that:

The infrared thermometer to measure a black body temperature of 273 k looking towards the horizon and 255 k looking directly towards.

Given that: The infrared thermometer to measure a black body temperature of 273 k looking towards the horizon and 255 k looking directly towards. Sigma T_P^4 = E sigma T_th^4 Hence, Long wave emissivity is E = [T_P/T_th]^4 [255/273]^4 0.76 because, slant angle is looking towards the horizon So, we can define optical depth by it's definition which is Natural logarithm of the ratio of incident to transmitted power. That is, T = Ln (I_0/I) \r\n 1/Ln[273/255]^4 1/Ln [1.313] 1/0.2728 3.66