06 Condesation and Cloud Formation Flashcards
Warm air rises
Hot air rises because when you heat air, it expands. When the air expands, the molecules move further apart and it becomes less dense than the air around it. The less dense hot air then effectively floats on top of the more dense cold air, which creates a buoyant force that causes warm air to rise.
Dew Point
A cloud will form when a parcel of air reaches dew point. Dew point is the critical temperature at which condensation occurs. The water vapour will change phase from gaseous to liquid. Latent heat is released as the water condenses. We describe the air as saturated once dew point is reached as it is at 100% relative humidity and cannot hold any more water as vapour.
The Atmosphere
The troposphere is the lowest portion of Earth’s atmosphere, and is also where all weather takes place. It contains approximately 75% of the atmosphere’s mass and 99% of its water vapour and aerosols.
Temperature of the air in the troposphere
The temperature of the air gets colder as you travel up through the troposphere, approximately 6.5OC per Km. However, it does not always decrease at this exact rate and it varies depending on factors such as height, season, and over surfaces (i.e. ocean or land)
Why does it not get hotter as you move closer to the sun?
The troposphere is primarily heated from the bottom because the surface is much better at absorbing a wide range of solar radiation as compared to the air. The surface is
What is the Environmental Lapse Rate (ELR)?
The Environmental Lapse Rate (ELR) is the rate of decrease in temperature with height in the atmosphere. It is affected by factors such as height, season, and whether the surface is over land or water. On average, the ELR is 6.4°C per 1000 m.
What is the Adiabatic Lapse Rate?
The Adiabatic Lapse Rate is the rate of decrease in temperature with height of a parcel of air that is not in contact with its surroundings. As the parcel of air rises and expands, it becomes cooler. The dry adiabatic lapse rate is approximately 10°C per 1000m and the saturated adiabatic lapse rate is approximately 5°C per 1000m.
What is the difference between stable and unstable parcels of air?
A parcel of air is considered stable if it is at the same temperature as the surrounding environment, and will stop rising and eventually sink down. A parcel of air is considered unstable if it is warmer than the surrounding environment, and will continue to
