Figure 4.

Predicted profiles of insect numbers within 10 m height intervals in a stably stratified nocturnal boundary layer, (a,d) 2 hours, (b,e) 4 hours and (c,f) 8 hours after climbing to 150 m and thereafter responding to gusts in vertical wind speed by climbing or descending in the direction of the gust with a vertical airspeed of w_f=0.3 m s⁻¹. In (d–f) this response arises when the vertical wind speed exceeds w_c=0.1 m s⁻¹, while in (a–c) the response threshold is w_c=0.3 m s⁻¹. Insects are predicted to preferentially concentrate at the top of the inversion layer where the air is fastest. The stable boundary layer has height z=200 m.