High school geography, why is London located near the twilight line during the day 19: 02 on July 27 (the answer is written, but how to calculate it? )

According to July 27th 19: 00 and 12: 00, we can calculate that the meridian at 0: 00 local time is 72 e, so the boundary that divides the world into two dates at this time is 72 e and international date line (180 longitude).

Know the relationship between the earth's rotation and revolution and the geographical significance of the earth's revolution.

1, the comparison between the earth's rotation and revolution;

2. Cape Huang Chi:

(1) The intersection angle between the equatorial plane and the ecliptic plane. At present, it is 23 26'

(2) The movement of the direct point of the sun between the Tropic of Cancer and the Tropic of Cancer.

3. The intersection angle between ecliptic and declination and its influence;

(1) has two important features during the earth's revolution:

The earth moves obliquely around the sun. Therefore, the earth's orbital plane (ecliptic plane) does not coincide with the equatorial plane, and the intersection angle between them is the ecliptic angle. At present, the declination angle is 23 26 ˊ.

(2) The direction of the earth's axis in space does not change with the seasons. The relative position of the sun and the earth is changing at any time, which causes the annual variation of the latitude position of the direct point of the sun.

(2) The intersection of the ecliptic and the earth: the direct point of the sun. This intersection is the northernmost summer solstice, the southernmost winter solstice and the equatorial vernal equinox.

(3) The influence of the ecliptic angle: Because of the existence of the ecliptic angle and the fact that the axis direction of the earth in space does not change with the seasons, the direct point of the sun moves back and forth between the tropic of cancer.

(4) The influence of the change of yellow-red intersection angle:

If the angle between yellow and red becomes larger, the range of direct sunlight will increase, the period of change of the length of day and night will be prolonged, and the difference between the four seasons will be more obvious. From the temperature zone, the direct range has expanded, that is, the tropical range has expanded. At the same time, the turning angle of the terminator line will also increase, and the range of extreme day and night will also increase, that is, the area of the cold zone will also increase, thus reducing the area of the temperate zone.

Similarly, if the intersection of yellow and red becomes smaller, the range of tropical and cold zones will be reduced and the range of temperate zones will be expanded. The change of temperature zone will inevitably have a great impact on the ecological environment. The climate and temperature suitable for some living things have changed fundamentally, and they may migrate on a large scale or even become extinct.

Focus on detailed explanation

-Interpretation of lighting diagrams

(1) judging the north and south poles is usually used in the top view. The basis of judgment is: the earth's rotation is counterclockwise from the North Pole and clockwise from the South Pole; Or look at the longitude, the direction in which the east longitude increases is the direction of the earth's rotation.

(2) Judging the solar terms, date and latitude of the direct point of the sun, the circle passes through the pole (or coincides with a meridian) in the morning and evening, and the direct point of the sun is the equator, that is, vernal equinox; The termination line is tangent to the polar circle. If there is an extreme solar phenomenon in the Arctic Circle, it is the summer solstice in the northern hemisphere, and the direct point of the sun is 23 26' north latitude. If there is extreme night in the Arctic Circle, it is the winter solstice in the northern hemisphere, and the direct point of the sun is at 23 26' south latitude.

(3) When determining the local time, in the illumination map, the meridian where the direct point of the sun is located is noon 12, the middle meridian of the daytime part surrounded by the terminal line is 12, the local time between the morning line and the equator is 6, and the meridian between the dark line and the equator is 18. According to every 15o, the time difference is 65438+.

(4) Determine the length of day and night to find the length of day (night) in a place, that is, to find the length of the sun (night) arc in the latitude circle, or to calculate it by the longitude of the sun (night) arc.

(5) To judge the height angle of the sun at noon, first find the latitude difference between the sought area and the direct point of the sun. If the sought area and the direct point of the sun are in the same hemisphere, take the latitude difference between the two places. If the searched area and the direct point of the sun are not in the same hemisphere, take the sum of the latitudes of the two places, and then use the latitude difference of 90o- to get the noon sun height of the searched area.

-Termination line and latitude and longitude.

(1) Judge the problem according to the intersection of the termination line and latitude.

① The terminator line passes through the north and south poles, and it can be judged that this day is around March 2 1 or September 23.

② The end line is tangent to the north and south poles, and it is daytime in the Arctic Circle. It can be judged that this day is around June 22, summer solstice in the northern hemisphere, summer in the northern hemisphere and winter in the southern hemisphere.

(3) The terminator line is tangent to the north and south poles, and it is night in the Arctic Circle. It can be judged that this day is around 65438+February 22, the northern hemisphere is winter solstice, the northern hemisphere is winter, and the southern hemisphere is summer.

(2) Judging the length of day and night according to the intersection relationship between the termination line and the meridian.

When calculating the day length or night length of a place, calculate the day length of the place from the intersection of morning line and latitude circle to the intersection of dark line and latitude circle in the daytime hemisphere, and divide the longitude by 15, which is the day length of the place. If only half a solar hemisphere is drawn on the map, it should be noted that the length of the day divided by 15 is twice the longitude difference of the day span.