However, it should be noted that due to changes in air pressure, relative humidity, and other quantities, the exact effects of atmospheric refraction on sunrise and sunset time cannot be predicted.
32.
In sunrise / sunset tables, the assumed semidiameter ( apparent radius ) of the Sun is 16 minutes of arc and the atmospheric refraction is assumed to be 34 minutes of arc.
33.
His other topics included a study of atmospheric refraction, stellar parallaxes, drawings of Jupiter, determination of the position of Mars'equator, the amount of its oblateness and the rate of motion of the nodes.
34.
"' Atmospheric refraction "'is the deviation of light or other electromagnetic wave from a straight line as it passes through the atmosphere due to the variation in air density as a function of height.
35.
:: : : Here's the quoute from the article I just finished Mirage of astronomical objects : " Due to a normal atmospheric refraction, sunrise occurs shortly before the sun crosses above the horizon.
36.
The sunrise equation, however, which is used to derive the time of sunrise and sunset, uses the Sun's physical center for calculation, neglecting atmospheric refraction and the non-zero angle subtended by the solar disc.
37.
Atmospheric refraction-the bending of the light from the Moon as it passes through the Earth's atmosphere-alters the observed declination of the Moon, more so at low elevation where the atmosphere is thicker ( deeper ).
38.
Dong writes that " at the time, this discovery was remarkably original . " Ibn al-Haytham, in his " Book of Optics " ( 1021 ), also discussed atmospheric refraction ( in regard to twilight ).
39.
Oriani's theorem explains why Cassini's uniform-density model works well except near the horizon the atmospheric refraction from the zenith to a zenith distance of 70?is not dependent on the details of the distribution of the gas.
40.
It does not allow for the fact that there may be a hill or wave in the way, and does not allow for the effects of atmospheric refraction-crucial in the case of Lake Constance as noted above.
