Final answer:
Leif Erikson and his men likely experienced more equal lengths of day and night because they set up camp in a higher latitude around 50°. They did not experience the full extent of polar daylight and darkness due to their location outside of the Arctic Circle.
Step-by-step explanation:
The days and nights where Leif Erikson and his men set up camp were of more nearly equal length compared to Greenland or Iceland, which would suggest the phenomena of polar daylight and darkness. Given the description that on the shortest day of winter, the sun was up between 7:30 and 3:30, and that there was little to no frost during winter, it could imply a higher latitude around 50°, but not within the Arctic Circle where the polar night or midnight sun could occur. The nearly equal length of day and night suggests that they might have been far north, but not so far as to experience continuous sunlight or the extreme conditions of polar regions.
The scenario described connects to the Earth's axial tilt and the way it influences the lengths of day and night due to its orbit around the Sun. Seasons and day lengths drastically differ at various latitudes as a result of this tilt. In regions closer to the poles, like where Erikson might have been, the differences between the lengths of days and nights can be significant but not as extreme as inside the polar circles.