The greatest temperature range would occur on the day when the skies were clear both during the day and the night. The smallest range in temperature would occur on the day when the sky was cloudy both during the day and the night. That is because clouds reflect and block some of the incoming sunlight, preventing the temperature from rising too high. Also, during the night, clouds block some of the heat from leaving the atmosphere, therefore there is not a big difference between the day and night temperature. On the contrary, the Earth's surface during a summer day with clear sky receives a lot of sunlight and it heats up. However, this cools down if the sky remains clear at night as well. In this case, there is a big temperature range.
