Calculation of places
Depending on the longitude, when calculating the place, the following steps can be followed:
(1) Judge the east-west direction. The earth rotates from west to east, and in the direction in which the earth rotates, it is east.
(2) Calculate the longitude difference between the two places. When the same east or west longitude is used, the values are subtracted; the values are added to one east longitude and one west longitude.
(3) When calculating places. Using the calculation method of "East plus West Subtraction", the addition method is used to calculate the place of the eastern region, and the subtraction method is used to calculate the western part; the longitude is 1° per interval, and the local time is 4 minutes apart.
Figure 1 Division of the world's 24 time zones
Xiaoming, who lives in Mudanjiang City (45°N, 130°E), posted a sunrise chart taken by the river (Beijing time) on the Internet, and read the picture to complete 1-2 questions.
1. The date of the day may be ( )
A． April 1
B． June 1
C． September 1
D． November 1
2. The sunrise direction of the day is ( )
A． southeast
B． northeast
C． East
D． southwest
Answer: D, A
Intensive analysis: (1) Calculate the sunrise time of the day. (1) As can be seen from the figure, the sunrise of 6:00 Beijing time in the area. The longitude of Beijing is 116 ° E, the longitude of the place is 130 ° E, the longitude of the place is > the longitude of Beijing, that is, the east of Beijing, the addition method is used when calculating the place of the place; (2) at sunrise, the local time of the place = (130 ° -116 °) ×4min + 6:00, that is, 6:56, that is, the local time of the place is 6:56 sunrise; (3) the place is sunrise at 6:56, later than 6 o'clock, so it is located in the winter half a year (autumn equinox ~ winter solstice ~ spring equinox), and the November 1 of option D is correct.
(2) Analyze the sunrise bearing. (1) At this time, It is November 1, that is, the winter half year, so the southeast sunrise and southwest sunset in the area are correct, and option A is correct; (2) the northeast sunrise in the summer half year, the sunrise due to the east of the spring equinox and the autumn equinox, so the other options are wrong.
Sunrise and sunset directions
The difficulty of the example questions in this section is moderate, and the solution ideas are: (1) According to the Beijing time of the sunrise in the place, combined with the longitude of the place, calculate the sunrise time (6:56) of the place, and compare with 6:00 to determine the date of the place (half a year of winter) ;(2) According to the date at this time, determine the direction of the sunrise.
Different seasons, the direction of the sun sunrise and sunset is different. In the Northern Hemisphere, for example, sunrise and sunset are:
(1) Summer half a year (spring equinox - summer solstice - autumn equinox): northeast sunrise, northwest sunset;
(2) Half a year of winter (autumn equinox - winter solstice - spring equinox): southeast sunrise, southwest sunset;
(3) Spring equinox/autumn equinox: due east sunrise, due west sunset.
The sunrise and sunset directions in the southern hemisphere are the same as in the northern hemisphere, but the trajectory of the sun in the northern hemisphere is shifted to the south, and the trajectory of the sun in the southern hemisphere is shifted to the north.
Figure 2 Directions of sunrise and sunset
[Every night at 20:00, one question per day, learn geography well]