The temperature on the bus

We usually do the bus, the bus has a display temperature and time of the electronic display screen at the same time. Do you know why the bus device thermometer? In the Shanghai bus and tram passenger management ordinance shall be specified in. Article 22 the vehicles equipped with air conditioning operating, the operator shall regularly maintain the vehicle air conditioning, maintain its good working condition, and prominently set around a car thermometer. June each year on September 30, a solstice during a solstice December and march during a day, and in the meantime car outside temperature above 28 degrees Celsius or below 12 degrees Celsius, operator shall open vehicle air conditioning. In addition to the provisions of the preceding paragraph shall open the case of vehicle air conditioning business operator shall open vehicle ventilation facilities.