I'd like to know how the state-of-the-art meteorological direct, localized measurements of the temperature of the air is measured.
If you put a thermometer in sunlight it may read high. If you put it in a box with some air vents it may also read high during the day and exhibit a time lag due to local trapping of air when there's no wind and due to radiation exchange with the thermal cavity in which it now sits.
If there's suspended droplets of water in the air it can condense or simply collect on surfaces and later evaporate which can act as a source or sink of heat with the thermometer.
The rate of heat exchange between the air and the thermometer is pretty low due to the relatively low density of air, so these other effects can significantly compete.
So I'd like to ask:
Question: How do meteorologists accurately measure outdoor air temperature?
Of course there are other ways to determine the average temperature of a geographically large amount of air of some significant thickness in height, but I'm asking about localized measurements at say a meteorological data collection station at an airport or other fixed site, collecting data for archival purposes or weather predictions, or even air temperature measurements from a system affixed to a weather balloon or aircraft used to collect data.