ATSC 110 Test 2 Study Guide with Complete Solutions

ATSC 110 Test 2 Study Guide with Complete Solutions Define stable and unstable when relating the terms to the atmosphere - Answer- Comparison of temperatures between a parcel of air and the air surrounding the parcel. Stable: When parcel of air is colder than the surrounding air, it will not be able to rise because its more dense or heavier than the surrounding air. If the parcel is forced to rise it will return to its place of origin once the lifting dissipates Unstable: When parcel of air is warmer than surrounding air, it will have buoyancy because it is less dense or lighter than the surrounding air and will be able to rise on its own. Define what an adiabatic process is? - Answer-When a rising parcel of air expands and cools or when a sinking parcel of air compresses and warms with no exchange of heat with the surrounding air outside of the parcel, this situation is called an adiabatic process. List the 3 lapse rates and their numerical values, that are used for a rising or descending parcel of air. - Answer-Dry Lapse rate (10c/km) EMILLECT 2024/2025 ACADEMIC YEAR ©2024 EMILLECT. ALL RIGHTS RESERVED FIRST PUBLISH OCTOBER, 2024 Page 2/10 Dew-point lapse rate (2c/km) Moist lapse rate (6c/km) List the lapse rate used for the vertical temperature profile of the atmosphere. - Answer- Environmental lapse rate, is not a constant number. The atmospheric temps are always changing, the calculation of the environmental lapse rate will vary What are the necessary conditions needed to determine the correct use of the various lapse rates for a parcel of air? - Answer-1. Dry lapse rate is used for a parcels temperature when the parcel of air is unsaturated (RH100%) -10c/km in a rising parcel and +10c/km in a sinking parcel. 2. Dew-point lapse rate is used for a parcels dew-point temperature when the parcel of air is unsaturated(RH100%). -2c/km in a rising parcel and +2c/km in a sinking parcel. 3. Moist lapse rate is used for the parcels temperature and dew-point temperature when the parcel of air reaches saturation (RH= 100%) -6c/km for a rising parcel. Why do we use 10˚C/km for the dry adiabatic lapse rate and only 6˚C/km for the moist adiabatic lapse rate? - Answer-Once the air parcel becomes saturated (100% RH) the latent heat of condensation(600cal/gr) will add sensible heat to the parcel which in turn will offset the cooling within the parcel. Hence the cooling rate will decrease from 10c/km (dry) to 6c/km (moist) Explain the difference between the dry lapse rate and the environmental lapse rate. How do we obtain the environmental temperatures in order to calculate the environmental lapse rates? - Answer-Dry lapse rate applies to the cooling or warming of a parcel of air that is rising or EMILLECT 2024/2025 ACADEMIC YEAR ©2024 EMILLECT. ALL RIGHTS RESERVED FIRST PUBLISH OCTOBER, 2024 Page 3/10 descending through the atmosphere. The dry lapse rate has a constant value. The environmental lapse rate indicates the overall vertical temperature profile of the atmosphere. These temperatures are measured twice daily by the release of radiosonde balloons at the various National weather service stations. Environmental lapse rates can and do change regularly and change from different layers of the atmosphere. What is an absolutely stable atmosphere? - Answer-When a parcel of air remains colder than the surrounding air while being lifted, we say the air is stable. What conditions cause a stable atmosphere? - Answer-The environmental lapse rate is small when stable conditions prevail. In other words the difference in the air temperature from the surface to those aloft is relatively small. Therefore we need warm air aloft or cool air at the surface or a combination of both to achieve this relatively small temperature decrease with height. What processes in the atmosphere can cause the atmosphere to become more stable? - Answer-1. Warm air advection above the surface 2. Downward movement of air above( subsidence) that will cause the air temperatures above to warm due to compression 3. Cold air advection on and/or near the surface 4. Overnight radiational cooling on the surface 5. Air moving over a colder surface which will cause the surface air temperature to decrease EMILLECT 2024/2025 ACADEMIC YEAR ©2024 EMILLECT. ALL RIGHTS RESERVED FIRST PUBLISH OCTOBER, 2024 Page 4/10 What kind of clouds are associated with a stable atmosphere? - Answer-When stable air is forced to rise it will have tendency to spread out. The clouds that form under this condition will also spread out forming layers. Clouds with this characteristic will be either cirrostratus, altostratus, stratus or nimbostratus. What is an unstable atmosphere? - Answer-When a parcel of air remains warmer than the surrounding air while being lifted, we say the air is unstable. In other words, when the environmental lapse rate is greater than the dry lapse rate (10°C/km) the atmosphere is absolutely unstable. What conditions cause an unstable atmosphere? - Answer-The environmental lapse rate is large (steep) when unstable conditions prevail. In other words the difference in the air temperature from the surface to those aloft is relatively large. Therefore we need cold air aloft and warm air at the surface to steepen the environmental lapse rate. What mechanisms can cause the atmosphere to become more unstable? - Answer-1. Cooling aloft by cold air advection above the surface. 2. Warming at the surface by daytime solar heating and warm air advection on the surface. On a typical summer day, how does atmospheric stability change from the daytime to nighttime? - Answer-During the daytime, incoming solar r