Why do leaves have dew?

Dew does not exclusively form on leaves, but rather on various surfaces exposed to the night sky, including leaves, grass, soil, cars, and more. The presence of dew is influenced by several key factors:

Humidity: For dew to form, there needs to be sufficient water vapor in the air. When the air is humid, it contains a higher concentration of water molecules.

Temperature: Dew forms when water vapor condenses into tiny droplets of liquid water. This process occurs when the temperature of the surface drops below the dew point, which is the temperature at which the air becomes saturated with water vapor and condensation begins. The dew point is affected by humidity; higher humidity levels lead to a higher dew point.

Clear Skies: Dew formation is most prominent on clear nights because the absence of clouds allows for better heat loss from the surface through radiation. Clouds can act as a barrier, preventing heat loss and hindering dew formation.

Radiation: During the day, the sun's heat warms the ground and other surfaces. When the sun sets and the sky becomes clear, the accumulated heat radiates back into the atmosphere. This cooling effect lowers the temperature of surfaces and promotes dew formation.

Wind: Wind can interfere with dew formation by mixing the air near the surface with warmer air above it, preventing the surface temperature from dropping as significantly. Calm winds or stagnant air favor the formation of heavier dew.

Location and Microclimates: The presence of dew can vary depending on the location and microclimates within a region. Factors like elevation, proximity to bodies of water, and localized topography can influence the temperature, humidity, and cooling patterns that affect dew formation.

So, while leaves often exhibit dew due to their exposed nature and the cooling effects of the night, it's not exclusive to leaves; rather, dew forms on various surfaces exposed to the appropriate conditions of humidity, temperature, clear skies, and radiative cooling.