Daily variations in temperature is the difference of the highest and lowest temperature on the same day. While the highest temperature during the day is in the afternoon, the lowest is before the sun rises due to the loss of heat. Moisture keeps heat during the day and prevents heat loss at night. Therefore, the places where the daily temperature difference is highest are deserts where the humidity and water presence is low.
Isobars and isotherms are both lines on weather maps that represent patterns of pressure and temperature. They show how temperature and pressure are changing over space. They describe the large-scale weather patterns across a region in the map.