From full light area to summer solstice

The solar terms with the largest illumination area vary from place to place. For example, this place is in the northern hemisphere, and the solar term with the largest illumination area is the winter solstice. If this place is in the southern hemisphere, the solar term with the largest illumination area is the summer solstice. The size of the lighting area is related to the solar altitude angle. The smaller the solar altitude angle, the larger the illumination area, and the larger the solar altitude angle, the smaller the illumination area.