The best comparison of the tone in these passages is:
Both passages have an alarmed, frightened tone.
The first passage describes a sense of dread and illness in the community, suggesting a serious concern for health and safety. The second passage, while discussing darkness as a natural state, could also imply a need for understanding nature and its balance, but does not come across as humorous or reassured. Thus, the overall tone of both passages conveys a form of alarm related to the subjects they address.