1 / 44

Lecturer: Prof. Elizabeth A. Ritchie, ATMO TAs: Ms. Simona Olson

NATS 101 Introduction to Weather and Climate Section 5: T/R 2:00 – 3:15 pm ILC 120. Lecturer: Prof. Elizabeth A. Ritchie, ATMO TAs: Ms. Simona Olson. Important Information. Office Hours : Prof. Ritchie – T/W 11:00-11:50 am or by appointment, PAS 570 Ph: 626-7843

dillian
Download Presentation

Lecturer: Prof. Elizabeth A. Ritchie, ATMO TAs: Ms. Simona Olson

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. NATS 101 Introduction to Weather and Climate Section 5: T/R 2:00 – 3:15 pm ILC 120 Lecturer: Prof. Elizabeth A. Ritchie, ATMO TAs: Ms. Simona Olson

  2. Important Information • Office Hours: Prof. Ritchie – T/W 11:00-11:50 am or by appointment, PAS 570 Ph: 626-7843 (except Aug 25 - Sep 14) Ms. Olson – T 3:30-5:00 pm & W 3:00-4:00 pm or by appointment, PAS 526 Ph: 621-6843 • Required Text: Understanding Weather and Climate, 4rd Ed. by E. Aguado and J. E. Burt

  3. Attendance Policy Attendance is mandatory, and I reserve the right to tally it throughout the term. http://catalog.arizona.edu/2006-07/policies/classatten.htm Attendance does go into your grade and can make the difference between a higher or lower letter grade if you are borderline.

  4. Student Behavior UA Code of Academic Integrity, Code of Conduct and Student Code of Conduct are enforced in this course. Every student is responsible for learning these codes and abiding by them.http://w3.arizona.edu/~studpubs/policies/ppmainpg.html Students can submit complaints online athttp://web.arizona.edu/~dos/uapolicies/

  5. Grading: Homeworks • There will be eight homeworks throughout the semester, which are to be downloaded and printed off from the Course website by each student. Dates when they become available, and when they are due are listed on the website.Homeworks are dueat the beginning of classon the dates shown. • The lowest score among the eight homeworks will be dropped from the course grade. *** THEREFORE, NO LATE HOMEWORKS WILL BE ACCEPTED ***

  6. Grading: Weather Diagram You will each prepare a time series chart of sea-level pressure (SLP) and temperature (T) observations recorded from the Tucson NWS office for the month beginning September 17. In addition, you will take your own personal observations of the weather every day noting special conditions, e.g., windy, rain, hot, cold, etc, and add these to the time series. You will prepare a half page text analysis of the observations discussing the relationship between the temperatures, sea-level pressures, and weather conditions of the day. Details of how you will accomplish this are provided on the course website. The neatly drawn, completed chart will be turned in with your second midterm exam for grading and credit. Note: you will need the weather diagram to answer questions on the midterm exam.

  7. Grading: Midterm Exams • There will be three midterm exams at regular intervals through the semester. These will occur on September 18, October 23, and November 20. These dates are listed in the course outline provided on the website. • Students who arrive late on midterm days will be not allowed to take the exam after the first student turns in her/his exam. NO EXCEPTIONS • The lowest score among the three midterm exams will be excluded from the course grade. *** THEREFORE, NO MAKE-UP EXAMS ***

  8. Grading: Final Examination Section 5 (2:00 pm T/R): ILC 120 December 16, 2:00 pm - 4:00 pm No Exceptions per UA Policy • The final will be comprehensive, covering all material from the course. • I suggest you double-check the date and time of this exam.

  9. Grading Algorithm • 25% Homework (lowest score dropped) • 15% Weather Diagram • 25% Midterm Exams (best 2 of 3 scores) • 25% Final Exam • 10% Class Participation NO EXTRA CREDIT PROJECTS. NO EXCEPTIONS. SO PLAN ACCORDINGLY!

  10. Course Grading • Course Grading Scale A 90% or higher B 80.0-89.99% C 65.0-79.99% D 55.0-64.99% E < 55.0%

  11. Lecture Notes: for the next lecture will be made available in a printer-friendly pdf format the afternoon after the current lecture is over. Print them off and bring them to class. The lectures are almost exclusively power-point-based and you will need the prints to make notes on

  12. The Golden Rule Instructor and students all show: Mutual Respect! What exemplifies respectful behavior? No talking Turn off cell phones/pagers/ipods… Arrive on time Remain seated until dismissed

  13. Literacy Requirements • Use scientific notation for writing numbers (especially rather large or small ones). For example: 1,000,000.0 should be written as 1.0 x 106. 0.00006 should be written as 6.0 x 10-5. • Specify units of physical quantities (e.g. meters for elevation, etc.). Marks will be deducted if units are missing. • Always show all working. A correct number pulled out of a hat will NOT receive full credit! • Basic algebra will be needed for some problems in this class. If you have trouble understanding how to do these problems, seek help early!

  14. Class Format:Lecture Days • 5-10 minutes - Announcements, Map Discussion and Forecast • 2-3 minutes - Review/Summary/Clean-up From Prior Lecture (Optional) • 60-65 minutes - New Material, Demos, Discussion • 2-3 minutes - Wrap-up and Summary

  15. Announcements Course Homepage…is functional! http://www.atmo.arizona.edu/ Click Course Links Click NATS101 – Ritchie All information pertaining to this course is contained on the webpage. Review problem sets and solution sets will be provided through the webpage. You should immediately get a U of A account if you do not already have one so that you can access this website and take advantage of the U of A computing facilities. All email correspondence to myself or the TA should be via your .arizona.edu email otherwise it risks being automatically deleted as spam mail.

  16. NATS 101Weather Brief

  17. Surface map showing weather observations (plotted using the station model notation), fronts and satellite cloud photographs

  18. Satellite cloud photographs with weather radar overlay

  19. Surface weather map with isobars (pressure contours) and fronts

  20. NATS 101Lecture 1Basic weather symbols and fronts

  21. We describe weather in terms of: temperature wind patterns humidity clouds visibility pressure precipitation sunlight/UV We “feel” weather as the heat we feel, the “weight” of the air we breathe. • If we observe these weather elements at an instance in time, then we obtain a measure of the weather • If we measure these weather elements over many years, then we obtain the “climate” of the region. • Therefore: • climate represents an average of daily weather over a long period of time • Weather is the instantaneous condition of the atmosphere.

  22. “Climate is what we expect” “Weather is what we get”

  23. Pressure and Wind • Atmospheric pressure impacts every aspect of weather although we do not easily recognize differences in pressure. • Air moves from high pressure to low pressure → wind • Air tends to rise in regions of low pressure and sink in regions of high pressure • Pressure Units: mb, hPa, inches Hg, mm Hg • Wind Units: m/s, mph, km/h, kts

  24. Temperature • - tends to change gradually in horizontal or vertical directions • also changes with time for the same weather system → diurnal cycle • the only place there are rapid changes in temperature is in the vicinity of fronts • Units:- °C, °F, K

  25. Moisture: water vapor • - Two common ways to express the amount of water vapor in the air • - Relative Humidity:- is the amount of water vapor in the air relative to the maximum amount that could be present in the air. Units: % • Dew Point Temperature:- • Td > 15°C is humid. • Td > 20°C is very uncomfortable. • Td < 5°C is dry.

  26. Surface Map: Cold air Cold air Cold air H L Warm air Warm air Warm air Pressure Systems: low pressure Fronts: high pressure Cold front Warm front Stationary front

  27. Upper-level Maps: 500 mb (hPa) (5 – 6 km or 16000 – 19000 ft)

  28. Upper-level Maps: 300 mb (hPa) (9 – 10 km or 30,000 – 33,000 ft)

  29. CH ff 34CM247 CH VV ppa dd TTCMPPP 30CLNh WRt VVwwppa N h RR TdTdCLNh WRt h RR Weather Map Symbols Ref:- pg 525, Appendix C, Aguado and Burt N – total cloud cover dd – wind direction ff – wind speed (kts) ww – present weather PPP – barometric pressure (hPa) (add a 9 or 10 and place a decimal point to the left of last number) TT– air temperature in °F TdTd - dewpoint temperature in °F Z (UTC) = MST + 7 i.e., 0000 UTC = 5:00 pm MDT 1200 UTC = 5:00 am MDT

  30. Some basics of Frontal Systems (Chapter 9) • Fronts are boundaries that separate air masses with differing temperature and other characteristics. 2. Often represent boundaries between polar and tropical air - marked by sharp temperature changes over a relatively short distance. • Cold air is typically more dense than warm air → no mixing. Instead, the denser air forces the warmer air upward. 4. This lifting of air upward can cause cloud formation and precipitation. 5. Fronts are marked by wind shifts. 6. Fronts are marked by pressure and pressure changes.

  31. Cooler air Cold air Warm air Cold air Cold air Cold air Warm air Warm air Warm air Types of fronts: Occluded front Fronts: Stationary front Cold front Warm front

  32. Cold air Warm air (relatively) Cold air advection Cold air 1 -5°C 0°C 5°C 2 -25°C -2°C 3°C Warm air 3 -28°C -12°C -5°C Cold Fronts Cold fronts occur when a cold air mass “catches up” with a warm, generally unstable, air mass. St. Louis Day Minneapolis Birmingham

  33. Cold Fronts The cold air mass moves in a different direction (W through N) than the warm air mass ( SW through S). It is also moving faster. The cold air catches up with the warm air and it… 1. pushes the warm, unstable air up because the cold air is denser 2. the cold air has a steep slope, because friction causes the lowest winds to slow down compared with winds higher up 3. unstable rising air mass produces cumulo-type (thunderstorm) clouds • - The thunderstorms can produce very intense precipitation. • They only form right along the frontal boundary, • the fast movement of these fronts means that the precipitation is usually of short duration and clearing skies will soon follow.

  34. South-southwesterly Gusty, shifting West-northwesterly Warm Sudden drop Steadily dropping falling steadily Minimum, then sharp rise Rising steadily Increasing cumulus-type clouds Strong cumulus clouds Often cumulus Short period of showers Heavy showers of rain or snow, sometimes with hail, thunder, and lightening Decreasing intensity, then clearing High: remains steady Sharp drop lowering So what would our observer on the ground expect to see and feel with the passage of a “classic” cold front? Weather element Before Passing While Passing After Passing Winds Temperature Pressure Clouds Precipitation Dew Point

  35. Warm air advection Cold air Warm air Warm Fronts Warm fronts occur when a warm, stable air mass “catches up” with a colder air mass. Warm air Cold air (relatively)

  36. The warm air is moving faster than the cold air. The warm air is less dense than the cold air The warm air “runs up” along the cold air boundary, which is not as steep as in the cold front case (over-running). There are three consequences of this. 3. The precipitation out of this stratiform type cloud tends to be light and continuous, but owing to the large horizontal area of the cloud, and slow movement of these kinds of fronts, the rain can persist for days. 2. The warm air is stable and so it doesn’t form cumulo-type clouds as in the cold front case. Instead, as it is forced to rise, it condenses gradually forming a series of stratiform clouds, in a broad area. 1. The clouds and precipitation form well ahead of the surface front.

  37. South-southeasterly variable south-southwesterly Cool – cold slowly warming Steady rise Warmer, then steady Usually falling Leveling off Slight rise, followed by fall Ci, Cs, As, Ns, St, fog Stratus-type clouds Clearing with scattered Sc Light-to-moderate rain, snow, sleet, or drizzle Drizzle or none Usually none, sometimes light rain or showers Steady rise steady Rise, then steady So what would our observer on the ground expect to see and feel with the passage of a “classic” warm front? Weather element Before Passing While Passing After Passing Winds Temperature Pressure Clouds Precipitation Dew Point

  38. No air advection Cold air Warm air Stationary Fronts Stationary fronts occur when the front stalls. The structure is the same as in other fronts, with the front sloping over the cold air mass. There is no air movement across the frontal boundary, thus, there is no real weather.

  39. Occlusion refers to “closure”. In this case, a faster moving cold front closes with the warm front. Occluded Fronts Are associated with midlatitude cyclones that have both a cold front and a warm front associated with them.

  40. Because at the surface, the cold air mass is now “catching up” with a cooler air mass rather than a warm air mass the temperature change observed at the surface is not as dramatic. As the cold front reaches the warm front, (and thus the cooler air in front of the warm front), the warm air mass is separated from the surface.

  41. An additional change is that now the warm, unstable air is no longer being strongly lifted by the cold front. The cooler air that has replaced the warm air at the surface is not unstable. Thus, where the occlusion has occurred, only stable stratiform cloud develops accompanied by light but persistent rain similar to the warm front.

  42. L Cooler air Cold air Warm air Occluded front Cold air Cold air Cold air Warm air Warm air Warm air Summary:- Types of fronts: Fronts: Stationary front Cold front Warm front

  43. Reading Assignment • Aguado and Burt Pages 21-26 Pages 525-527 (Appendix C)

More Related