Metrology [sic, sadly not even my spell checker knows the science of measuring] for Meteorology and Climate (MMC) organizes a webinar on how f-ing hard it is to measure air temperature outside. https://www.meteomet.org/events/waiting-for-mmc-webinar/
The metrologists normally take care we know how long a meter exactly is and measure parameters with 10+ digits.
As a climatologist it is a real pleasure to see them sweat and realize how hard it is to measure the temperature of an isolator (air) exposed to all the elements.