Final answer:
Dew forms on grass when the temperature drops to the dew point, leading to a localized decrease in entropy as water vapor condenses into liquid, but the total entropy of the universe still increases due to the second law of thermodynamics.
Step-by-step explanation:
The phenomenon of dew formation on blades of grass is related to the concept of entropy in physics. When the air temperature drops to or below the dew point, the air can no longer retain all the water vapor it held at higher temperatures, leading to the condensation of water vapor into dew drops. This process is associated with entropy because when water vapor condenses into liquid form, there is a decrease in the disorder of the system, which implies a decrease in entropy. However, the second law of thermodynamics states that for a macroscopic system, the overall entropy must increase. Therefore, while the local entropy decreases when dew forms, the entropy of the surrounding environment increases by a greater magnitude, ensuring that the total entropy of the universe still increases.
The dew point is crucial because it dictates when water vapor will condense. This typically results in heat transfer, affecting temperature stabilization and is especially important for farmers monitoring potential frost conditions. Furthermore, in local systems on Earth, energy transferred from external sources, like the Sun, can lead to decreases in local entropy without violating the second law, because the total entropy, including the surrounding environment, increases.