Lab 6: Atmospheric Instability

Important Things to Remember for Every Lab: - Always show your work for calculations - Always use and show the correct units - Be sure to read the entire question and answer it fully; This document does not cover everything - Answer all questions in the manual unless told otherwise

Background: You should register at meted.ucar.edu for tutorials on reading the more complex versions of skew-T diagrams. It is free and takes only a few seconds to sign up. This will help you immensely because this lab is very difficult. URL for skew-T lesson is: http://www.meted.ucar.edu/mesoprim/skewt/

Figure 1:

600

700

800 Pressure (mb)

10 −

900

0 2 1000 −10 0 10 20 Temperature (C)

For Questions 1-5, you are using Figure 3 on the next page (it’s colored!)

Question 1: Remember temperature is the slanted line the goes to the right as you go up in altitude. Your green curve is the dew point and the red curve is the environmental temperature.

Question 2: You have to reference the mixing ratio lines for this question (green dashed line). Cross out the word “environmental” in the directions here.

Question 4: Round to the nearest tenth.

Question 5: Hint: Think of why we are interested in these three things. Give an example of what we hope to find when we are looking at them.

Figure 3: 2 461015 g/kg 400 7

18 1

500 21

5 10

Altitude (km)

600 4 25

20 Pressure (mb) 700 3

800 2

10 LCL 30 900 1

0 1000 2 20 30 Temperature (C)

Figure 4:

400

500

600

20 Pressure (mb) 700 LFC

800

10 LCL 30 900

0 1000 2 20 30 Temperature (C)

For questions 6-14, you are using Figure 6. Do not use the black and white version in the book because it has some errors. Please use this colored version below or the one I printed for you.

Figure 6: 0.5 1 2 g/kg 100 16 4

90 − 40 30 15 70 − − − 6 14

80 13 − 8 50 − 60 12 − 200 10

11 12

40 30 20 70 − − − 10 − 15

Altitude (km) 300 9 10 18 −

50 − 8 0 21

Pressure (mb) 6 0 400 7 25 40 30 20 − − − 500 30 10 5 10 − 600 4 35 0 20 700 3

30 20 − − 800 2

10 10 900 − 30 1

1000 0 20 −30 −20 −10 0 10 20 30 40 Temperature (C)

Question 6: You must show all four of your calculations in the space next to this question. For the third one, it should read -30 degrees Celsius, not 30 degrees Celsius. Be sure that you are putting HEIGHT in the denominator and not pressure. When you are doing this, you might not always be exactly ON the wet adiabatic line. You have to run parallel to it.

Question 9: Remember you are using Figure 6, not Figure 5. Answer this in terms of pressure.

Question 10: You are basically reiterating how to do this AND what it means conceptually when you find the LCL (but you have to do these things in your own words).

Question 11: Answer the question but also give me the actual temperature of both the parcel and the environment at the pressure level of the LCL.

Question 15: Do not use today’s most recent sounding. Use the one I have provided for you below. Do not plot this on the Figure 5 in the lab manual, but in the colored blank skew-T I have given you. Mark your LCL, EL, and LFC as labeled dots on the graph. The important features I want you to discuss are: 1) The relative humidity at 800 mbar. 2) The approximate moist adiabatic lapse rate at 800 mbar and 15 °C. 3) The height in kilometers at which you would expect the bottom of a cloud base to be if you raised air from the surface and cooled it adiabatically. 4) Whether the clouds you formed from adiabatic cooling would be positively or negatively buoyant 5) The pressure level at which the clouds will be the same temperature as their environment

Here is the sounding data:

Pressure (mb) Temp (°C) Dew Point (°C) 1000 15 4 900 18 1 800 4 -7 700 -2 -18 600 -13 -32 500 -26 -34 400 -37 -39 300 -48 -53 200 -58 -65 100 -60 -82