#Computes the flux of photons at wavelengths
#shorter than a given value stated in nanometers

import math
from ClimateUtilities import *
import planets,phys

#Some useful conversion factors
evJoules = 1.60218e-19 #1 electron volt in Joules
evAttoJoules = .160218 #1 electron volt in attojoules


#Orbit and stellar data
TSun = 5780.
rSun = 6.955e8  #Move these to planets module
Afact = (rSun/planets.Earth.rsm)**2

#Work in units of 1/nm instead of frequency, so
#the romberg integrator doesn't get confused by
#big or small numbers when applying convergence criterion.
#For same reason, leave out division by h until later.
def fPhotons(waveNum,T):
    nu = phys.c*waveNum*1.e9
    #The following is OK becaue dnu/nu = dWaveNum/WaveNum
    #It is correct also to put the factor of pi here, since
    #we compute the flux at Earth's radius by finding the total
    #power output of the Sun and dividing by the area of the sphere
    #with radius equal to the Earth's orbit
    return math.pi*phys.B(nu,T)/waveNum

m = romberg(fPhotons,100) #Use more starting divisions to resolve tail

def photons(WaveLen):
    return Afact*m([1./WaveLen,1./10.],TSun)/phys.h