If the temperature and dewpoint are within 2°C of each other, what weather phenomenon would you expect?

When the temperature and dewpoint are within 2°C of each other, it indicates that the air is nearing saturation, meaning the relative humidity is very high. This close proximity suggests that the air is almost at its moisture-holding capacity. When this condition prevails, the likelihood of condensation increases, leading to the formation of clouds and ultimately fog.

Fog forms when the air cools to its dewpoint, causing the moisture in the air to condense into tiny water droplets suspended in the air. This process occurs most often in calm weather conditions where the air has minimal disturbance, and the moisture levels are sufficient to create visibility-reducing fog.

Clear skies would typically be associated with drier air and a larger disparity between temperature and dewpoint. A cold front passage can lead to significant weather changes, but it does not specifically correlate with this temperature-dewpoint relationship. Thunderstorms also require other conducive conditions, such as instability and lift, which aren't directly indicated by the proximity of temperature and dewpoint.

Therefore, understanding that close temperature and dewpoint readings signal high humidity helps to connect the phenomenon of fog with these atmospheric conditions.