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This macro computes the length of the day, from sunrise to sunset. Sunrise/set is considered to occur when the Sun's upper limb is 35 arc minutes below the horizon (this accounts for the refraction of the Earth's atmosphere). |
This macro computes the length of the day, including civil twilight. Civil twilight starts/ends when the Sun's center is 6 degrees below the horizon. |
This macro computes the length of the day, incl. nautical twilight. Nautical twilight starts/ends when the Sun's center is 12 degrees below the horizon. |
This macro computes the length of the day, incl. astronomical twilight. Astronomical twilight starts/ends when the Sun's center is 18 degrees below the horizon. |
This macro computes times for sunrise/sunset. Sunrise/set is considered to occur when the Sun's upper limb is 35 arc minutes below the horizon (this accounts for the refraction of the Earth's atmosphere). |
This macro computes the start and end times of civil twilight. Civil twilight starts/ends when the Sun's center is 6 degrees below the horizon. |
This macro computes the start and end times of nautical twilight. Nautical twilight starts/ends when the Sun's center is 12 degrees below the horizon. |
This macro computes the start and end times of astronomical twilight. Astronomical twilight starts/ends when the Sun's center is 18 degrees below the horizon. |
Note:
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Note:
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Computes the Sun's ecliptic longitude and distance at an instant given in d, number of days since 2000 Jan 0.0. The Sun's ecliptic latitude is not computed, since it's always very near 0. |
This function reduces any angle to within the first revolution by subtracting or adding even multiples of 360.0 until the result is >= 0.0 and < 360.0 Reduce angle to within 0..360 degrees |
This function computes GMST0, the Greenwich Mean Sidereal Time at 0h UT (i.e. the sidereal time at the Greenwhich meridian at 0h UT). GMST is then the sidereal time at Greenwich at any time of the day. I've generalized GMST0 as well, and define it as: GMST0 = GMST - UT -- this allows GMST0 to be computed at other times than 0h UT as well. While this sounds somewhat contradictory, it is very practical: instead of computing GMST like: GMST = (GMST0) + UT * (366.2422/365.2422) where (GMST0) is the GMST last time UT was 0 hours, one simply computes: GMST = GMST0 + UT where GMST0 is the GMST "at 0h UT" but at the current moment! Defined in this way, GMST0 will increase with about 4 min a day. It also happens that GMST0 (in degrees, 1 hr = 15 degr) is equal to the Sun's mean longitude plus/minus 180 degrees! (if we neglect aberration, which amounts to 20 seconds of arc or 1.33 seconds of time) |
Compute the altitude of the sun. No atmospherical refraction taken in account. Altitude of the southern hemisphere are given relative to true north. Altitude of the northern hemisphere are given relative to true south. Declination is between 23.5° North and 23.5° South depending on the period of the year. Source of formula for altitude is PhysicalGeography.net http://www.physicalgeography.net/fundamentals/6h.html |
Compute the maximal solar flux to reach the ground for this date and latitude. Originaly comes from Environment Canada weather forecast model. Information was of the public domain before release by Environment Canada Output is in W/M^2. |
Subroutine computing the part of the equation of time needed in the computing of the theoritical solar flux Correction originating of the CMC GEM model.
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Description: Statement function that calculates the variation of the solar constant as a function of the julian day. (dAlf, in radians)
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Generated by Epydoc 3.0.1 on Sun Mar 15 16:26:39 2009 | http://epydoc.sourceforge.net |