View Source Astro.Earth (Astro v1.0.0)
Constants and astronomical calculations related to the earth.
Summary
Functions
Adjusts the solar elevation to be the apparent angle
at sunrise if the requested angle is :geometric
(or 90°)
Returns the radius of the earth in kilometers
Adjusts the solar elevation to account for the elevation of the requested location
Returns the obliquity of the earth
Returns an estimate of the effect of refraction applied to the calculation of sunrise and sunset times.
Returns the suns apparent radius at sunrise/sunset.
Functions
Adjusts the solar elevation to be the apparent angle
at sunrise if the requested angle is :geometric
(or 90°)
Arguments
solar_elevation
is the requested solar elevation in degress. It will be 90° for sunrise and sunset.elevation
is elevation in meters
Returns
- The solar elevation angle adjusted for refraction, elevation and solar radius.
Returns the radius of the earth in kilometers
Adjusts the solar elevation to account for the elevation of the requested location
Arguments
elevation
is elevation in meters
Returns
- The solar elevation angle adjusted for the elevation
@spec nutation(Astro.Time.julian_centuries()) :: Astro.angle()
Returns the obliquity of the earth
Returns an estimate of the effect of refraction applied to the calculation of sunrise and sunset times.
Sunrise actually occurs before the sun truly reaches the horizon because earth's atmosphere refracts the Sun's image. At the horizon, the average amount of refraction is 34 arcminutes, though this amount varies based on atmospheric conditions.
This effect is especially powerful for objects that appear close to the horizon, such as the rising or setting sun, because the light rays enter the earth's atmosphere at a particularly shallow angle. Because of refraction, the sun may be seen for several minutes before it actually rises in the morning and after it sets in the evening.
Returns the suns apparent radius at sunrise/sunset.
Unlike most other solar measurements, sunrise occurs when the Sun's upper limb, rather than its center, appears to cross the horizon. The apparent radius of the Sun at the horizon is 16 arcminutes.