I am envisioning a habitable world with an atmosphere comparable to earth's in which one day is extremely long (>100 earth years). Human settlers have successfully colonized a small portion of the planet near the equator, and have adapted to living in perpetual sunlight. They have not, however, been around long enough to experience nighttime on this planet.
When the colonist's part of world finally does enter nighttime, how will the climate change (specifically temperature)? Or will it change at all? How would it affect the colonists? I have read that Venus's lack of dramatic temperature shifts has something to do with its slow rotation. It seems to me like the more time a portion of the planet spends in darkness away from the sun, however, the more time that portion has to cool down. The way I understand it, the colonists would eventually be plunged into several decades of freezing temperatures.
Let's assume that a habitable planet with 100-year-long days isn't scientifically infeasible, and that all other life on the planet has adapted to these conditions. How does the length of a day impact temperature variations between day and night?