When the temperature and dew point spread is 4°F (2°C) or less, what weather condition becomes likely?
Why →
The dew point is the temperature at which air becomes saturated (100% relative humidity) and condensation begins. When the temperature-dew point spread narrows to 4°F (2°C) or less, the air is near saturation. Further cooling from overnight radiation, advection, or uplift will cause condensation as fog, low clouds, or precipitation.The trap →
Dry air has a large temperature-dew point spread. A small spread means nearly saturated air. The opposite of dry. High winds and turbulence are associated with unstable atmospheric conditions, not saturation.SOURCE → PHAK Chapter 12, Weather TheoryCHECKED APR 21ACS III.A.K1MED