C# 计算太阳倾角、太阳高度角

        /// 计算太阳高度角ho
        /// </summary>
        /// <param name="φ">当地纬度，度(如34.64)</param>
        /// <param name="t">北京时间，时(如9)</param>
        /// <param name="δ">太阳倾角，度(如-23.1)</param>
        /// <param name="λ">当地经度，度(如34.64)</param>
        /// <returns>返回太阳高度角，度</returns>
        public double ho(double φ, int t, double δ, double λ)
        {
            //公式：ho=arcsin[sinφsinδ+cosφcosδcos(15t+λ-300)]
            double a = 15 * t + λ - 300;//时角
            double b = Math.Cos(φ * Math.PI / 180d) * Math.Cos(δ * Math.PI / 180d) * Math.Cos(a * Math.PI / 180d);
            double c = Math.Sin(φ * Math.PI / 180) * Math.Sin(δ * Math.PI / 180);
            double d = c + b;
            double ho = Math.Asin(d) / (Math.PI / 180d);
            return ho;
        }

        /// <summary>
        /// 计算太阳倾角δ
        /// </summary>
        /// <param name="dn">一年中日期序数(0,1,2......364)</param>
        /// <returns>返回太阳倾角，度</returns>
        public double δ(int dn)
        {
            //公式：δ=[0.006918-0.399912cosQo+0.0702578sinQo-0.006758cosQo+0.000907sin2Qo-0.002697cos3Qo+0.001480sin3Qo]*180/π
            //Qo=360dn/365，度
            double Qo = Convert.ToDouble((Convert.ToDouble(360 * dn) / Convert.ToDouble(365)) * (Math.PI / 180d));
            double a = 0.399912 * Math.Cos(Qo);
            double b = 0.0702578 * Math.Sin(Qo);
            double c = 0.006758 * Math.Cos(Qo);
            double d = 0.000907 * Math.Sin(2 * Qo);
            double e = 0.002697 * Math.Cos(3 * Qo);
            double f = 0.001480 * Math.Sin(3 * Qo);
            double g = 180 / Math.PI;

            double h = 0.006918 - a + b - c + d - e + f;
            double δ = Math.Round(h * g, 1);
            return δ;
        }

https://blog.csdn.net/u012531272/article/details/54410247