Chapter 6

Rain Measurement and Sampling

Outline:

• Precipitation basics
  • Requirements for rainfall
    • Moisture saturation and nuclei
    • Cooling mechanisms
  • Forms of precipitation
  • Spatial and temporal variability
  • World records
  • Rainfall simulators
• Point measurement methods
  • Non-recording gages: NWS 8" diameter gage
  • Recording gages
    • Tipping bucket rain gages
    • Weighing bucket precipitation gages
    • Float and pressure transducer gages
    • Optical gages
  • Siting factors
    • Turbulence
    • Obstructions

Textbook reading:

• none.

Other reading:

• Precipitation. In (Brakensiek, D. L., Osborn, H. B., and Rawls, W. J., eds.) 1979. Field Manual for Research in Agricultural Hydrology. United States Department of Agriculture, Agricultural Handbook #224, p. 1-45.download here
• Click Here to view the tipping bucket on-line demonstrations

Related web links:

• Theory
  • Rainfall and its variability
  • Rainfall variability in Australia
  • Precipitation Variability at High Spatial Resolution in the Desert Southwest
  • World Rainfall Extremes
• Field Methods
  • 8-inch non-recording standard rain gage description
  • Tipping Bucket gage demonstration Asos tipping bucket rain gage
  • Method for estimating effective rainfall rate
  • NEXRAD Radar information
• Data Sources
  • National Climate Data Center- may cost $$$

CCM3 T170 Cloud and Precipitation Simulation

This 3.5-minute video shows a cloud and precipitation simulation of the Earth's coupled Ocean-Atmosphere-Land system. I am asking you to watch this video, because I want you to pay attention to the unique timing, pattern, and duration of cloud cover in different regions of the world.  Think about this: what is the weather pattern of Arizona, California, India, Yemen, and Scotland?  When you set up field data collection for precipitaiton, it is essential to have a strong conceptualization for how a process works. A video like this helps you figure that out. You can find more information about this video and higher resolution versions at this web link.

Video Podcast: Precipitation Measurement and Sampling, Part 1

This 16-minute presentation introduces a few basic ideas about precipitation that are useful to be mindful of before you try to measure it.

• 640 x 480 (480p) format that balances speed and quality. (161 MB file)
• 1920 x 1280 (HD) format that provides larges size and best quality. (1.3 GB file)

Video Podcast: Precipitation Measurement and Sampling, Part 2

This 28-minute presentation explains the different technologies available to measure and sample precipitation, especially rainfall.

• 640 x 480 (480p) format that balances speed and quality. (299 MB file)
• 1920 x 1280 (HD) format that provides larges size and best quality. (2.8 GB file)

Last Chapter  :  Assignment 2