Why is the lamp lit at noon, and what does this suggest about Paul and Ellen's situation?

For the past three days, strong winds have been making a wailing sound reverberate through the house. The wind also kicks up dust on the prairie; the dust is thick as fog, blocking light to the home and making it necessary to light a lamp during what should be the brightest part of the day. This effects the family both mentally and physically, and it also effects the farm.... and its crops.