Diurnal temperature variation and heat transfer
Daily cycle (FAA AWH 7.6), lag in heating and cooling of near-ground air:
- Peak insolation: around noon.
- Maximum surface air temperature: usually mid-afternoon.
- Minimum surface air temperature: usually shortly after sunrise.
Diurnal temperature variation (FAA AWH 7.6):
| Factor | Maximized | Minimized |
|---|---|---|
| Surface | Land | Water |
| Latitude | Low | High |
| Sky | Clear | Cloudy |
| Air | Dry | Moist |
| Wind | Light | Strong |
Maximizing conditions also favour radiation inversion.
How heat moves (AWH 5.6):
| Process | Moves heat |
|---|---|
| Radiation | through space, by electromagnetic waves |
| Conduction | by contact, one substance to another |
| Convection | by fluid motion, e.g. rising warm air |
Advection is horizontal transfer by wind (AWH 13.4.1).
Trap: Sun peaks at noon, but surface air peaks mid-afternoon (heating lag).
References
- FAA Aviation Weather Handbook (FAA-H-8083-28)