• 论文 •

### 坡地等日照时间和等日照方位的解析研究

1. 南京大学大气科学系, 南京　210008
• 出版日期:1997-09-15 发布日期:1997-09-15

### AN ANALYTICAL STUDY ON EID AND ESA ON A SLOPE

Sun Hanqun, Fu Baopu

1. Department of Atmospheric Sciences, Nanjing University, Nanjing 210008
• Online:1997-09-15 Published:1997-09-15

Abstract: In this paper, the authors study the existing conditions, ranges and distributional laws of the EID and ESA on a slope with an analytical method. EID (Equal Insolation Duration) means that the insloation duration on a slope is not variable according to the data. In the other words, the insolation duration on a slope is equal in every day of a year. ESA (Equal Sunshine Azimuth) is the azimuth of a slope on which EID is existing. The insolation duration of a slope is relative to the sunrise and sunset hour angles ω1, ω 2 . ω1 and ω2 are composed of the sunrise and sunset hour angies ωs1 , ωs2 on the non horizental surface and the sunrise and sunset hour angles - ω0, ω0 on the horizental surface. There are many different combined relations. For a slope with given latitude, gradient α and slope azimuth β , the combined relation can vary with the sun declination δ . When one combined relation changes into another one, there are two critical sun declinations δc . They meet the following condition: tan2δc= sin2 cos2φ/(1- sin2βcos2φ) Becaus the sun declination δ vary on the range of (-23.45°,23.45°), the following relation is necessary for δc existing: sin 2βcos 2φ≤ sin223.45°On the other hand, when sin 2β cos 2φ> sin 223.45°,we can not get the critical sun declination δc.

Key words: EID, ESA, slope

• P422.11