ATMS 360 Homework and Course Deliverables (return to main page)
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Assignment 7

The goal of this quick-study active-note-taking discussion is to become familiar with meteorological radar used to detect precipitation and severe weather.
Examples are on this page for composite reflectivity and for the Reno NWS dual polarization radar measurements.
Example of Doppler image for Des Moines Iowa.

Submission is through webcampus. Copy these questions to MS word and work on them.
Be sure to give your sources for answers.
Basics:
1. What is the diameter range for raindrops?
2. What is the diameter range for drizzle drops?
3. What is the diameter range for cloud droplets?
4. What is the shape of raindrops?
5. Why don't raindrops get arbitrarily large?

Local Rain Measurements:
6. What is the rainfall rate equation?
7. How does a simple rain gauge work?
8. How does a tipping bucket rain gauge measure rain?
9. How does a disdrometer work?

Weather Radar.
Weather radar presentation as powerpoint and as a pdf document for understanding radar and dbZ.

10. What is the name of weather radars used by the National Weather Service?
11. What is the wavelength range used by this radar?
12. Briefly, how does radar work to measure rain?
13. Calculate the size parameter x=2 pi * Raindrop Radius / radar wavelength.
14. What 'radiation regime' is the size parameter of question 13? Note that it is the same radiation regime that gives rise to the blue sky on a clear day. Note.
15. What is the basic relationship for radar backscattering in terms of number of raindrops per volume, back scattering strength, droplet diameter D, and radar wavelength lambda? Note.
16. Why must the radar be empirically calibrated for rainfall rate given question 15, and question 6?
17. How does Doppler radar work? What can be detected with it?
18. How does dual polarization radar work, and what can be detected with it?
19. What is the correlation coefficient as used in meteorological radar?
20. What does this correlation coefficient indicate?

Resources:

Great discussion of radar and its applications. (local backup).
What's under the dome? Discusses also the rotation of the radar.
Notes on differential polarization and the correlation coefficient associated with it.
National Weather Service discussion of weather radar.
Understanding radar discussion from the weather underground.

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Assignment 6: Near-surface weather stations

Purpose:

Become familiar with near-surface weather stations:
UNR weather station on Valley Road
- Changes of the surroundings affect the wind measurements?
Moderately expensive solar-powered weather station with 2D sonic anemometer for wind measurement (Ambient WS-5000)
- Measurement accuracy?
RM Young 3D sonic anemometer for fast measurements of horizontal wind, pressure, and temperature
- Turbulent kinetic energy and heat flux in addition to 3D wind components.

Lab Report with the Following Contents:

Part 1:
UNR weather station on Valley Road
- Use Google Earth (View: Historical) and get images of the UNR weather station for recent and past times. Explain how the area has changed and how that may impact wind measurements.
- Obtain and interpret UNR weather station data for the last 7 days.
Part 2: (read about measurements of temperature, pressure, and wind)
Moderately expensive solar-powered weather station with 2D sonic anemometer for wind measurement (Ambient WS-5000).
RM Young 3D sonic anemometer for fast measurements of horizontal wind, pressure, and temperature.
- Compare measurements of temperature, pressure, wind direction, and wind speed for these two instruments. Note especially the ability to measure low wind speeds in the stillness of the night.
- Data from Jan 1 to Jan 17 2026 for this assignment.
- Data example from the past. Raw and processed data comparison.
Part 3: Questions for discussion and exploration in your lab report (read further about lab reports for Atmospheric Sciences)
- What are some of the factors affecting near surface meteorology measurements over many years?
- Asses the WS-5000 weather station measurement accuracy assuming the RM Young 3D sonic anemometer is a measurement standard.

Additional Resources For This Assignment:

1. Style guide for lab reports.

2. UNR and DRI atmospheric instruments and measurement sites.

3. Atmospheric Instruments Textbook: See Appendix A on lab reports
Free through UNR Library: Online textbook for atmospheric instrumentation.

4. Relationships for wind speed and direction calculations.

5. RM Young sonic anemometer wind direction for U, V, and W winds (horizontal and vertical components).

Related Resources:

6. Wind roses to show wind direction and speed in single graph. (Python script and example data for it from the UNR weather station.)

7. Acquire and plot surface weather measurements as a function of time and location. Example of December 2025 minimum and maximum temperatures.

8. Note that tipping bucket precipitation measurements can distort the timing of snow in winter months (snow melts and is measured during day light hours).

Assignments 1 - 5 Online (see webCampus)

Assignment 5 Online (see webCampus) precipitation estimates.

Purpose: Become familiar with precipitation estimate measurements.

Assignment 4 Online (see webCampus) atmospheric radar measurements.

Purpose: Introduction to radar use in meteorology.

Assignment 3 Online (see webCampus) measurement of wind.

Purpose: Become familiar with atmospheric wind measurements.

Assignment 2 Online (see webCampus) measurement of atmospheric temperature.

Purpose: Become familiar with atmospheric temperature measurements.

Assignment 1 Online (see webCampus) Overview of Atmospheric Instrumentation.

Purpose: Broad overview of atmospheric instrumentation measurements.
This is an online homework assignment and is described on webCampus.

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