Final answer:
To identify the time of day in a picture, one must analyze the Sun's position, the length and direction of shadows, and the quality of the light. Short shadows around midday indicate noon, while long shadows and soft light suggest morning or evening. Dark settings with little to no activity typically represent night.
Step-by-step explanation:
When determining the time of day in a picture, we must observe the position of the Sun in relation to the horizon and any shadows that are present. If the Sun is near the horizon, it might be either morning or evening. If the shadows are very long and the sunlight appears soft and angled, it is likely morning or evening. Conversely, at noon, the Sun reaches its highest point in the sky, and shadows will be at their shortest. In the transition between morning to afternoon (before noon), the time is designated as a.m. (ante meridiem), and after the Sun crosses the meridian, it is known as p.m. (post meridiem). The presence of long shadows and soft light may also indicate it's early morning, suggested by the painting "Early Sunday Morning." Lastly, the lack of activity and dark empty spaces in the painting "Nighthawks" indicates it's the middle of the night.