MET 4300/5355 Severe Weather

Lecture 1 Introduction

Course Organization• Tu/Th 11:00AM-12:15 PM, Zoom (Canvas)• Haiyan Jiang, 305-348-2984,

AHC5 Rm371, haiyan.jiang@fiu.edu• Office Hours Tu 12:15-1:15 PM, or by email appointment• Previous General or Introduction to MET course.• On-line course materials at:

http://faculty.fiu.edu/~hajian/MET4300/MET4300.html• WxChallenge:

– Overview: http://tcpf.fiu.edu/Jiang/education/wxchallenge/FIU_WxChallenge.pdf

– Local manager: Rigo Olivera (roliv053@fiu.edu);– Signup deadline: Sep. ??, 2020– FIU website: http://tcpf.fiu.edu/Jiang/education/wxchallenge/index.html

Honesty Statement• FIU defines academic misconduct in the Student

Conduct and Honor Code (Code) as, “any act or omission by a Student, which violates the concept of academic integrity and undermines the academic mission of the University in violation of the Code.” Code violations include, but are not limited to: academic dishonesty, bribery, cheating, commercial use, complicity, falsification, and plagiarism. The Code is available here: https://studentaffairs.fiu.edu/get-support/student-conduct-and-academic-integrity/student-conduct-and-honor-code/index.php

Zoom Virtual Class Meetings• All students are expected to attend class meetings

through Zoom on Tu/Th at 11am-12:15pm.• If you are unable to attend a class meeting through

Zoom for any reason, I ask that you let me know beforehand via email.

• I strongly encourage you to turn on your camera during our class meetings on Zoom. By doing so, our time together will feel more like a face-to-face meeting, and it will help us cultivate a sense of community.

• During our class meetings, use the “chat” function on Zoom to ask questions, share your responses to the questions I pose, and share your comments about the day’s lesson. Let’s make our lessons and discussions as engaging and rich as possible!

Zoom Class Recordings• We will record our class lectures by using the

Cloud recording feature through Canvas. Hopefully you’ll be able to review the Zoom videos after each class via a link through Canvas.

Safe Participation Statement• We recommend students attend the Zoom

sessions in a quiet location where they may actively participate. In all cases, NEVER attend the Zoom session while operating a motor vehicle.

Grades:Grading Factors

Participation 10%Term-paper

(Graduate) 10%

Exam #1 20%

Exam #2 20%

Final 50%(Under)40% (Graduate)

Total 100%

Absence:

• Need a valid excuse (in-class exercises are counted toward your grade)

Graduate Term Paper• You will write a short literature review paper on a research topic of your choice, which

should be related to your thesis or dissertation research topic. It’s also preferable if your topic has something to do with the knowledge you’ll learn in this class, but it is not required. You don't have to include any results of yourself (You absolutely can if you do). Instead, you should just write a background review of this topic. You should find about 10 reference papers in this topic, and read them carefully and summarize their research methods & findings. Your paper should be 5-10 pages long (single-spaced, font size 12).

• 1. Please email me your paper title and a list of reference papers by Tuesday Oct. 13, 2020. I'll give you suggestions after I see your list.

• 2. You will need to give a class presentation about your term paper in class on Nov. 24, 2020. You will be given 15 min to present your paper & about 10 more minutes for questions from the audience.

• 3. Please email me your final term paper to me by Friday Dec. 11, 2020.

Text:

Textbook:• 27 chapters: we’ll cover 23 of them• Special sections in each Chapter:

1). List of learning Objectives2). Check your understanding3). Test your understanding4). Test your problem solving skills5). Focus box (case, advanced topics, etc.)

Suggestions• Preview the chapter• Read the text, start with learning

objectives• Pay attention to “check your

understanding” questions while reading

• Try to answer “Test your understanding” questions after reading the chapter

• “Test your problem-solving skills”

Class Activities:

• From “Active Learning Exercises” book

• We’ll do it in class as part of the lecture

Exams:

• Total 3 exams: Exam 1, 2, and final

• Final exam: time provided by same on Panthersoft (Dec. 8 (Tu) 9:45am-11:45am)?

Course Focus: Severe & Hazardous Weather

Course Topics

• 1/3 of the whole course will cover some very basic meteorology concept (lec 1-11; textbook CH1-9)

• The rest: different types of severe & hazardous weather including lee cyclone, northeasters, ice storms, lake-effect snow, cold waves, blizzards, mountain snowstorms, mountain windstorms, thunderstorms, tornadoes, hailstorms, lightning, and downbursts.

What is severe weather?

• Large, damaging hail (20 mm, or ¾ in)

• Damaging winds (60 mph, 50 kt, or 25 m s-1)

• Tornado• Or all of the above• Strong updrafts!

Severe Weather = “MESOSCALE” Weather

• Meso = Middle, between Macro- and Micro-scale

• Or between “Synoptic” and “Convective”• Actually includes Convective scale, too.• Horizontal scale is determined by surface

properties or natural scales of convective systems

• Vertical scale is defined by the depth of the troposphere.

What is Hazardous Weather?

• The definition is much broader than severe weather.

• Hazardous weather includes all types of weather that has hazardous impacts.

• It includes almost all scales of weather systems, not only mesoscale.

MET SCALES

Scales of Atmospheric MotionScale Length Time

Planetary ~6000 km (Re) Weeks

Synoptic ~ 2000 km days to a week

Meso-α 2000-200 km A day or two

Meso-β 200-20 km A day-hours

Meso-γ 20-2 km Hours-minutes

Convective 5 km – 500m Minutes

Micro < 2 km Minutes-seconds

Orlanski, 1975

Planetary Waves

Synoptic-ScaleWeather in 1863

Synoptic-Scale Weather

Meso- β

Radar, which maps hydrometeors (primarily rainfall) is a key instrument for understanding the mesoscale

Meso-Antiyclone

Gust Front

Gust front: the leading edge of cool air rushing down and out from a thunderstorm.

Downslope wind (Chinook, snow eater) is a wind directed down a slope, often used to describe winds produced by processes larger in scale than the slope.

Suction vortex are really substructures of many, perhaps all, tornadoes but are not always easily visible. These occur, usually, at the base of the tornado vortex where the tornado makes contact with the surface.

Dust devil is a strong, well-formed, and relatively long-lived whirlwind, ranging from small (half a metre wide and a few metres tall) to large (more than 10 metres wide and more than 1000 metres tall). The primary vertical motion is upward. Dust devils are usually harmless.

Summary• Severe weather

– Large, damaging hail (20 mm, or ¾ in)– Damaging winds (50 kt, or 25 m s-1)– Tornado– Or all of the above

• Hazardous weather: include all scales of weather• Scales of motion

– Planetary & synoptic—balanced > 2000 km– Mesoscale---nonbalanced, 2000-2 km– Convective—buoyant motions, 5-0.5 km (scale height)– Microscale---near surface < 1 km