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The near‐surface evening transition

Understanding of the evening boundary‐layer transition has increased substantially in the past few years although such progress has led to new questions particularly regarding the evolution of the wind field. Results from the literature and analyses of measurements from three contrasting sites in our study suggest that the near‐surface temperature evolution of the evening transition begins with a late afternoon period of slow cooling. Subsequent reversal from upward heat flux to downward heat flux is followed by a period of rapid cooling. This rapid cooling typically occurs over a 60–90 min period, mostly before sunset, and accounts for much of the total ‘nocturnal cooling’. The rapid cooling subsequently transitions into slow cooling that can last for the rest of the night. The details of the temperature evolution vary substantially between sites and vary between nights at a given site.