The solar terms in the northern hemisphere on this day

(1) When the earth revolves around the sun, the direct sunlight point moves regularly between the tropic of cancer in a year. When the earth is in position A, the latitude of direct sunlight is the Tropic of Cancer. The northern hemisphere is the winter solstice, with the shortest day and the longest night; There is an extreme night phenomenon in the Arctic Circle;

(2) When the sun directly hits the Tropic of Cancer (around June 22nd), it is the summer solstice in the northern hemisphere, which is the longest day and the shortest night;

(3) When all parts of the earth are equal in length of day and night, the direct point of the sun is at the equator, and the earth is at points B and D; At this time, the solar terms in the northern hemisphere are vernal equinox and autumnal equinox respectively;

(4) From May 1 day to June 1 day, the direct point of the sun is located in the northern hemisphere and continues to move northward.

So the answer is: (1) Tropic of Capricorn; Solstice of winter; Extreme night; (2)C； (3)B； d； Vernal equinox; Autumnal equinox; (4) the north; North.