ATOC 184 Lecture Notes - Lecture 5: Lapse Rate, Fluid Parcel, Dew Point

• School: McGill University
• Department: Atmospheric & Oceanic Sciences
• Course: ATOC 184
• Professor: Eyad Atallah

Document Summary

Rate at which an unsaturated parcel of air cools as it rises and expands: descending air will always warm by 10 degree c/km. Because no phase change occurring in descending air. Let"s consider an example: let"s start with a parcel with a temperature of 20 c and a dewpoint of 10 c, first, we lift the parcel until it is saturated. Note: dewpoint temperature cannot be higher than actual temperature => lost water vapor. This is equivalent to ~0. 2 mm of rain. The faster we are losing air parcels/faster air rises, the heavier the precipitation is. Why this is important: when clouds form, 2 things can happen: In general, the faster the rate of ascent to more rain/snow you get. The more latent heat that is released, the stronger storms tend to be. This is particularly true for thunderstorms and hurricanes.