ATOC 1070: Weather Lab FALL 2019

1. ATOC 1070: Weather Lab FALL 2019

2. Some questions we’ll answer in 1070 • Why is the sky blue and the sunset reddish? • Why do air pumps get warm? • Why are strong winds so destructive? • What influences a hurricane’s track, intensity, and impact? • How can you predict severe thunderstorms? • How do greenhouse gases keep us warm?

3. Lab CalendarFall 2019

4. If you are sick, let your TA know ASAP. If you have appropriate documentation, you will allowed to attend a lab section later in the week if one fits your schedule and has room in it for you. DO NOT just show up to another lab without your TA’s permission! They are very full.

5. The Lab Director is Dr. Derek Brown (derek.brown@colorado.edu). Please contact Dr. Brown if you have broader questions about the lab that are out of scope for your TA.

6. Who Are You? Talk with your table partners and find out: • Name and year in school • Goal(s) for taking this course • What have you always wanted to know about the weather or climate?

7. Insert your info here!

8. Class Overview • Teaching philosophy • Teach to different types of learners • Promote critical thinking through experimentation, discussion, and writing • Expectations • Attendance & participation • Time spent per Lab Report: 1-2 hrs for most • Critical thought • Writing • Goals • To understand that experiments contain errors, and learn to critically evaluate how and why these happen • To observe and analyze weather & climate phenomena

9. Syllabus Key Points • You must attend lab sessions and there will be no make-ups without good reason (documented illness, etc.). • One lab will be dropped • Canvas will be our main source for submitting lab reports, taking quizzes, and viewing your grades. You must submit your report as one document only (with graphs/tables embedded within) • Lab reports should be submitted as Word or PDF documents only. No Google Drive links, Rich Text, Pages, etc.

10. Lab writeups • Web pages of each lab report will be available on Canvas at least one week before the lab is performed • A syllabus is on your Canvas site: this has detailed instructions for writing lab reports, which we will take a look at today

11. Working together vs. cheating • Your data will be the same as your lab partners’ data • Write everything else (objectives, answers, conclusions) individually • Cheating (duplicated answers) = 0 • Honor Council referral 1st time • Fail the class 2nd time • Be aware that Canvas automatically will check your report against all other reports ever submitted here. You, the student, can see this plagiarism report when you submit the report.

12. Grading • Final grade: average of the best 10 lab reports (out of 11 total) • Each person turns in their own typed lab report for 6 of the labs • 5 of the labs will not have a lab report due, but instead you will take a Canvas quiz and/or submit the graphs or tables electronically that you made during the experiment • Lab grades • worth 100 pts. each • due by the start of the next lab (late reports lose pts.) • Questions/concerns? Please email or see me!

13. Grading • “Correct” answers not automatically worth full points • Must give coherent reasoning if asked • Calculations and units shown • Complete sentences where appropriate • Spelling/grammar/punctuation

14. Lab Report Requirements • On first page • Your Name • Lab Name • Section Number • Partners’ Names

15. Lab Report Requirements • Objectives • What are the learning objectives for this lab? • summarized in your own words in paragraph form • Data (Excel table and/or graphs) • Embedded into the main Word or PDF document • Questions • Complete answers where appropriate • Calculations with correct units • Conclusion • 4 questions (see next page and/or syllabus)

16. General Conclusion Requirements Did you accomplish the objectives that your experiment aimed to address? If not, explain why the experiment was a complete failure. What are some physical sources of error in the experiment? Describe at least 2 sources of error for each experiment that requires a lab report. How could the physical sources of error affect the outcome? You must address each source of error individually, and discuss how each affected the outcome. Tie what you have learned during this lab with your experiences with weather phenomena, climate patterns, or general science The conclusion is where much of the critical thinking takes place, and your grade will reflect how much effort you put into thinking about the lab results & sources of error

17. Microsoft Office • Many of labs will use Microsoft Excel & Powerpoint • Word documents are preferred for the method that you submit your lab report in (PDF also allowed). • Our lab computers have Office software, so that you can complete your tasks while at the lab • Outside of the lab, if needed, you have full access to this software as a CU student • Office online has major limitations. Follow this link to get the full desktop Office versions instead: https://oit.colorado.edu/services/messaging-collaboration/microsoft-office-365/help/proplus

18. Any questions regarding class policies? If not … let’s look a bit at precipitation, terminal velocity, and a sample lab on that subject

19. Instrument: Disdrometer • Active laser beam • Measures drop diameter • Measures fall speed • During a long descent, gravitational and air resistance forces become balanced, which leads to a terminal velocity for each drop

20. Terminal VelocityGravitational force • Fgravity∝ mass ∝ volume∝ R3 If the radius grows just a bit, the mass and thus downward force grows extremely quickly So the downward force for a solid (non-hollow) sphere increases with R3

21. Terminal VelocityAir resistance force • Fair ∝ ‘cross section’ • Cross section area ∝ R2 If the radius grows just a bit, the amount of air it hits and thus upwards force grows pretty quickly So the upward force for a falling sphere increases with R2

22. Terminal VelocityAir resistance force • Fair ∝ velocity2 The faster the drop goes, the amount of air it hits and thus upwards force grows pretty quickly So the upward force for a falling sphere increases with V2 as well As a drop falls, eventually a speed will be reached where the forces balance. This is terminal velocity

23. By using this info, we can equate the two forces to see what the terminal velocity will be once forces are balanced Recall that one force was ∝R3 and one was ∝R2, so you are left was an R in the solution So, the terminal velocity for raindrops is related to their size The letter k here represents a ‘constant’ in a lab setting

24. k is definitely not constant in the real world. What might speed up a drop’s fall rate in the real world other than it’s radius?

25. Splitting of liquid drops • Density of drop or stone • Density of air it is falling through • Changes in gravity • Aerodynamics These are fairly well controlled for in the lab, however the data did deviate substantially from theory all the same…

26. Lab Setting In the lab setting (9 foot ceiling), many big drops simply don’t have time to reach terminal velocity (blue oval) For both the lab and in nature, its common for small drops to go faster than our theory predicts (red ovals). Why do you think that is the case? Natural Setting

27. What do you think is happening here near the end of the video?

28. Activities (Graphs) • The TA posted two graphs • The students embedded these graphs into their main lab report for submission • For many labs, you’ll be making an Excel graph and/or spreadsheet and embedded it into a main report

29. Lab Report • Recommendation: write your report the day you do the lab • Easier to finish in 1 hour • Objectives • Activity • Questions • Conclusion (the specific conclusion in this sample lab is different than the general conclusion for most labs)

30. Sample Lab • Now that you have an idea about the setup and the theory….please check out the sample lab writeup & the sample lab submission on Canvas before your Lab 1 is due (week of September 16th) • This will greatly help your own writeups this semester

31. Excel Example • Open up ‘TermVeloc_Worksheet.docx’ and ‘TermVeloc.xlsx’ from the SAMPLE LAB Module of Canvas • Work through quick exercise with partners and TA. Show final result to TA. • When you are done, you are free to leave. See you in 2 weeks at our first graded lab: Lab 1!