The solar altitude angle in Beijing

The geographical coordinates of Beijing are: 39 "26' north latitude to 41"03' north latitude, which is about 40 "north latitude.

In winter solstice, the direct sunlight is 23 26', and the noon sun height in Beijing is 90-| 40-(-23 26') | = 26 34'.

The direct sunlight in summer solstice is 23 26 ′ n, and the noon sun height in Beijing is 90-| 40-23 26 ′| = 73 26 ′.

In the spring and autumn, the sun shines directly at the equator 0, and the height of the sun at noon in Beijing on that day is 90-| 40-0 | = 50.

At noon, the altitude angle of the sun is 12, which is the angle between the sun's rays and the ground.

Extended data:

1, vernal equinox: the fourth of the 24 solar terms, March 20th or 21; Mid-spring, the length of day and night is equal.

The vernal equinox is the midpoint of 90 days in spring. Every year around February 15 of the lunar calendar, when the sun is located at 0 of the yellow meridian (vernal equinox).

On the vernal equinox, the sun shines directly at the equator of the earth, and the seasons in the northern and southern hemispheres are opposite. The northern hemisphere is the vernal equinox and the southern hemisphere is the autumnal equinox.

The vernal equinox is a new year in Iran, Turkey, Afghanistan, Uzbekistan and other countries, with a history of 3,000 years.

2. Summer solstice: the fourth of the 24 solar terms, June 2 1 or 22; It means that the heat is coming, with the longest day and the shortest night.

On the solstice in summer, the direct sunlight on the ground reaches the northernmost point of the year and almost directly reaches the Tropic of Cancer. At this time, the day in the northern hemisphere is the longest, and the farther north it is, the longer it is.

China folks divide 15 days from summer to the future into three "hours", usually the first three days, the middle five days and the last seven days. During this period, the temperature in most parts of China was high, the sunshine was sufficient, the crops grew rapidly, and the physiological and ecological water demand was high. At this time, the precipitation has a great influence on agricultural output, and there is a saying that "raindrops are worth tens of millions in summer solstice".

3. Autumn Equinox: The sixteenth day of the twenty-four solar terms falls on September 23rd or 24th; It means that in the crisp autumn, day and night are equal.

At the autumnal equinox, the climate in the south begins to enter autumn from this solar term. On this day, the sun reaches the longitude of 180 degrees, and points directly at the equator of the earth, so the day is divided into 24 hours, each with 12 hours; There is no extreme day and night phenomenon in the world.

After the autumnal equinox, the polar night range near the North Pole and the polar sun range near the South Pole gradually expanded. Twenty-four solar terms: "In mid-August, see the vernal equinox" and "the points are equal, which is 90 days and a half, so it is called points." Half a minute is the midpoint of ninety days in autumn.

4. Winter solstice: the 22nd solar term in 24 solar terms falls on 65438+February 20th or 22nd, 265438+; It means that winter is coming, with the shortest day and the longest night.

The winter solstice, also known as "Winter Festival" and "Happy Winter", is one of the eight astronomical solar terms, which is opposite to the summer solstice. When the sun reaches 270 degrees, the winter solstice begins. According to legend, the solstice in winter is the New Year's Day of the Zhou Dynasty in history, and it was once a very lively day.