39. Among the following solar terms, the shadow of the awning on the parking space at noon is A. vernal equinox B. summer solstice C. autumn equinox D. winter solstice.

In the northern hemisphere, the biggest solar term in the shadow of parking spaces at noon is the winter solstice. This is because during the winter solstice, the height angle of the sun is the lowest and the shadow of shading is the longest. With the movement of the direct point of the sun, the height angle of the sun will gradually increase, and the shadow of shading will gradually become shorter. Therefore, option D, winter solstice, is the solar term with the largest shading shadow for parking spaces at noon.