Saturation and atmospheric stability lab 6 answers

Name: _ _ _ _ _ _ _ _ _ _ _ _ __ Laboratory Section: _ _ _ _ _ _ __ Date: _ _ _ _ _ _ _ _ _ _ _ _ __ Score/Grade: _ _ _ _ _ _ _ _ _ __ Video Exercise 13 Pre-Lab Video ~~ ~~ LAB EXERCISE http://goo.gVTs9HM5 Scan to view the Stability and Adiabatic Pre-Lab video Processes Humidity and temperature characteristics of an air mass are key parameters in determining the stability of the air. Conditions in the environment determine whether a mass of air will lift, cool by expansion, and become saturated-unstable conditions-or whether it will resist displacement-stable conditions. This exercise examines stability aspects of air masses and adiabatic processes. Lab Exercise 13 has three sections. Key Terms and Concepts adiabatic dry adiabatic rate (DAR) environmental lapse rate (ELR) lifting condensation level moist adiabatic rate (MAR) normal lapse rate orographic lifting rain shadow stability KEYLEARN I NGconcepts After completion of this lab, you should be able to: • Contrast environmental lapse rates with adiabatic processes to calculate the stability of an air mass. • Define dew-point temperature, saturation, and lifting condensation level. • Identify the processes that lead to condensation, cloud development, and precipitation . • Evaluate orographic lifting effects and apply adiabatic heating and cooling rates. Materials/Sources Needed pencils calculator Copyright C 2018 Pearson Education, Inc. colored pencils Lab Exercise 13: Stability and Adiabatic Processes 107 ·111 Applied Physical Geography: GeosyS t ems in the Laboratory Lab Exercise and Activities SECTION 1 Atmospheric Stability Stability refers to the tendency of an air parcel to rise, remain in place, or fall . A parcel that is warmer than the air around it is unstable, and it will rise until it reaches an altitude where the air around it has a density and temperature similar to its own. A stable parcel will either stay where it is or sink. The normal lapse rate and the environmental lapse rate (ELR) refer to the change in temperature with_increasing altitude through the troposphere. The normal lapse rate is the average decrease in temperature with increase in altitude through the troposphere , measured at 6.4 C0 /1000 m (3 .5 F°/1000 ft) . The environmental lapse rate (ELR) is the actual lapse rate at a particular place and time and varies by several degrees per thousand meters . The adiabatic rates refer to the change in temperature of a moving parcel of air. Adiabatic means occurring without a loss or gain of heat between the surrounding environment and the vertically moving parcel of air. A rising parcel of air cools by expansion because of lower air pressure at higher altitudes. Sinking air heats by compression. The two adiabatic lapse rates depend on the moisture conditions in the parcel: the dry adiabatic rate (DAR) and the moist adiabatic rate (MAR) . The dry adiabatic rate (DAR) is the rate at which "dry" air cools by expansion (if ascending) or heats by compression (if descending). "Dry" refers to air that is not saturated and has less than 100% relative humidity. The DAR is 10 C0 /1000 m (5 .5 F°/1000 ft) . The moist adiabatic rate (MAR) is the rate at which a rising saturated air parcel cools by expansion. The average MAR is 6 C0 /1000 m (3 .3 F° /1000 ft) . This is roughly 4 C0 (2 F°) less than the dry adiabatic rate because of roughly four degrees of heating from the latent heat of condensation. As a saturated parcel of air rises and cools, water vapor condenses and releases the latent heat of condensation, forming a cloud. The altitude at which condensation occurs is the lifting condensation level. Determining stability involves comparing the temperatures of an air parcel and the surrounding air. The rate of cooling of a parcel compared to the environmental lapse rate determines the stability of the atmosphere . The following two proble~s involve each of the possible conditions: stable (1f the risino air is cooler than or the same temperature as the surrounding air) , unstable (if the rising air is warmer than the surrounding air). and conditionally unstable . (if, in rising , the air becomes warmer than the surrounding air only after it begins cooling at the MAR) . The basic temperature relationships that determine stability conditions in the atmosphere between the environmental lapse rate and dry and moist adiabatic rates are shown in Figure 13 .1. The normal lapse rate (remember: it's an average) , the DAR, and MAR are plotted according to their respective formulas. The curved set of arrows shows the overall possible range within which the actual environmental rate might fall. If the environmental lapse rate of the air surrounding a rising parcel of air is greater than the DAR (i.e., > 10 C /1000 m) , the rising air will remain warmer than the surrounding environment, will be unstable (a). and will continue to rise. If the environmental lapse rate is less than both the DAR and the MAR (i.e., < 6 C0 /1000 m) , the rising column of air will be cooler than the surrounding air (which is cooling at the environmental rate) and will be stable (c) , resisting further rising. and instead will settle back to its original position. In the circumstance that the environmental rate is between the MAR and DAR ( > MAR and < DAR). the parcel of rising air will resist rising as long as the air remains unsaturated; however,