def extraterrestrial_irrad(utc_datetime, latitude_deg, longitude_deg,SC=SC_default):
"""Equation calculates Extratrestrial radiation. Solar radiation incident outside the earth's
atmosphere is called extraterrestrial radiation. On average the extraterrestrial irradiance
is 1367 Watts/meter2 (W/m2). This value varies by + or - 3 percent as the earth orbits the sun.
The earth's closest approach to the sun occurs around January 4th and it is furthest
from the sun around July 5th.
Parameters
----------
utc_datetime : date_object
utc_datetime. UTC DateTime is for Universal Time ( i.e. like a GMT+0 )
latitude_deg : float
latitude in decimal degree. A geographical term denoting the north/south angular location
of a place on a sphere.
longitude_deg : float
longitude in decimal degree. Longitude shows your location in an east-west direction,relative
to the Greenwich meridian.
SC : float
The solar constant is the amount of incoming solar electromagnetic radiation per unit area, measured
on the outer surface of Earth's atmosphere in a plane perpendicular to the rays.It is measured by
satellite to be roughly 1366 watts per square meter (W/m^2)
Returns
-------
EXTR1 : float
Extraterrestrial irradiation
References
----------
.. [1] http://solardat.uoregon.edu/SolarRadiationBasics.html
.. [2] Dr. J. Schumacher and et al,"INSEL LE(Integrated Simulation Environment Language)Block reference",p.68
"""
day = solar.GetDayOfYear(utc_datetime)
ab = math.cos(2 * math.pi * (solar.GetDayOfYear(utc_datetime) - 1.0)/(365.0))
bc = math.sin(2 * math.pi * (solar.GetDayOfYear(utc_datetime) - 1.0)/(365.0))
cd = math.cos(2 * (2 * math.pi * (solar.GetDayOfYear(utc_datetime) - 1.0)/(365.0)))
df = math.sin(2 * (2 * math.pi * (solar.GetDayOfYear(utc_datetime) - 1.0)/(365.0)))
decl = solar.GetDeclination(day)
ha = solar.GetHourAngle(utc_datetime, longitude_deg)
ZA = math.sin(latitude_deg) * math.sin(decl) + math.cos(latitude_deg) * math.cos(decl) * math.cos(ha)
return SC * ZA * (1.00010 + 0.034221 * ab + 0.001280 * bc + 0.000719 * cd + 0.000077 * df)
def GetRadiationDirect(utc_datetime, altitude_deg): # from Masters, p. 412 if(altitude_deg > 0): day = solar.GetDayOfYear(utc_datetime) flux = GetApparentExtraterrestrialFlux(day) optical_depth = GetOpticalDepth(day) air_mass_ratio = GetAirMassRatio(altitude_deg) return flux * math.exp(-1 * optical_depth * air_mass_ratio) else: return 0.0
def subsolar_point(ut):
'''
A routine to calculate the subsolar point.
Input: ut = datetime holding the current UT
Output: sslon = Subsolar Longitude (degrees)
sslat = Subsolar Latitude (degrees)
'''
# subsolar latitude is given by the solar declination
doy = solar.GetDayOfYear(ut)
sslat = solar.GetDeclination(doy)
# subsolar longitude occurs at noon SLT
hour = ut.hour + ut.minute / 60.0 + ut.second / 3600.0
sslon = 15.0 * (12.0 - hour)
if sslon > 360.0:
sslon -= 360.0
if sslon < 0.0:
sslon += 360.0
return (sslon, sslat)
def declination_degree(utc_datetime, TY = TY_default ):
"""The declination of the sun is the angle between Earth's equatorial plane and a line
between the Earth and the sun. It varies between 23.45 degrees and -23.45 degrees,
hitting zero on the equinoxes and peaking on the solstices.
Parameters
----------
utc_datetime : date_object
utc_datetime. UTC DateTime is for Universal Time ( i.e. like a GMT+0 )
TY : float
Total number of days in a year. eg. 365 days per year,(no leap days)
Returns
-------
DEC : float
The declination of the Sun
References
----------
.. [1] http://pysolar.org/
"""
return 23.45 * math.sin((2 * math.pi / (TY)) * ((solar.GetDayOfYear(utc_datetime)) - 81))
def mean_earth_sun_distance(utc_datetime):
"""Mean Earth-Sun distance is the arithmetical mean of the maximum and minimum distances
between a planet (Earth) and the object about which it revolves (Sun). However,
the function is used to calculate the Mean earth sun distance.
Parameters
----------
utc_datetime : date_object
utc_datetime. UTC DateTime is for Universal Time ( i.e. like a GMT+0 )
Returns
-------
KD : float
Mean earth sun distance
References
----------
.. [1] http://sunbird.jrc.it/pvgis/solres/solmod3.htm#clear-sky%20radiation
.. [2] R. aguiar and et al, "The ESRA user guidebook, vol. 2. database", models and exploitation software-Solar
radiation models, p.113
"""
return (1 - (0.0335 * math.sin(360 * ((solar.GetDayOfYear(utc_datetime)) - 94)) / (365)))
def GetSunriseSunset(latitude_deg, longitude_deg, utc_datetime, timezone):
"""This function calculates the astronomical sunrise and sunset times in local time.
Parameters
----------
latitude_deg : float
latitude in decimal degree. A geographical term denoting
the north/south angular location of a place on a sphere.
longitude_deg : float
longitude in decimal degree. Longitude shows your location
in an east-west direction,relative to the Greenwich meridian.
utc_datetime : date_object
utc_datetime. UTC DateTime is for Universal Time ( i.e. like a GMT+0 )
timezone : float
timezone as numerical value: GMT offset in hours. A time zone is a region of
the earth that has uniform standard time, usually referred to as the local time.
Returns
-------
sunrise_time_dt : datetime.datetime
Sunrise time in local time as datetime_obj.
sunset_time_dt : datetime.datetime
Sunset time in local time as datetime_obj.
References
----------
.. [1] http://www.skypowerinternational.com/pdf/Radiation/7.1415.01.121_cm121_bed-anleitung_engl.pdf
.. [2] http://pysolar.org/
Examples
--------
>>> gmt_offset = 1
>>> lat = 50.111512
>>> lon = 8.680506
>>> timezone_local = 'Europe/Berlin'
>>> utct = dt.datetime.utcnow()
>>> sr, ss = sb.GetSunriseSunset(lat, lon, utct, gmt_offset)
>>> print 'sunrise: ', sr
>>> print 'sunset:', ss
"""
# Day of the year
day = solar.GetDayOfYear(utc_datetime)
# Solar hour angle
SHA = ((timezone)* 15.0 - longitude_deg)
# Time adjustment
TT = (279.134+0.985647*day)*math.pi/180
# Time adjustment in hours
time_adst = ((5.0323 - 100.976*math.sin(TT)+595.275*math.sin(2*TT)+
3.6858*math.sin(3*TT) - 12.47*math.sin(4*TT) - 430.847*math.cos(TT)+
12.5024*math.cos(2*TT) + 18.25*math.cos(3*TT))/3600)
# Time of noon
TON = (12 + (SHA/15.0) - time_adst)
sunn = (math.pi/2-(23.45*math.pi/180)*math.tan(latitude_deg*math.pi/180)*
math.cos(2*math.pi*day/365.25))*(180/(math.pi*15))
# Sunrise_time in hours
sunrise_time = (TON - sunn + time_adst)
# Sunset_time in hours
sunset_time = (TON + sunn - time_adst)
sunrise_time_dt = date_with_decimal_hour(utc_datetime, sunrise_time)
sunset_time_dt = date_with_decimal_hour(utc_datetime, sunset_time)
return sunrise_time_dt, sunset_time_dt