Rain, Sleet, and Hail Size and Density Monitor
For Weather, Aircraft, Transportation, Paints, Surfaces
An instrument for continuous monitoring of the size and density of rain drops and sleet and hail pellets.
The monitor measures the number of rain drops/pellets per square inch per second, the average mass of the rain drops/pellets over time, the mass of each individual droplet/pellet, and calculate droplet/pellet sizes and mass and size distributions. Up to eight probes (locations) per monitor.
Characteristics
Droplet/Pellet size: 1 micron and larger
Droplet/Pellet weight: 10^-13 grams and higher
Detecting Probes: up to 8 per monitor
Applications
Atmospheric processes: Detection of rain, sleet and hail, weather research, special surveys of solid and liquid particulate deposition (aerosols and droplets) such as in weather and acid rain research
Aircraft and ground vehicle monitoring: Erosion, safety (monitor installed on a moving vehicle)
Weathering and erosion testing: Paint, surface finish and material tests
Description
The monitoring method is based on detection of minute shock waves produced by the impact of solid or liquid particles on a probe. A transducer converts these waves, which are proportional to the kinetic energy, K.E., of the impacting particles, into electrical signals.
K.E. = ½mv^2 (m = mass, v = impact velocity)
A schematic of the monitoring equipment is shown in Figure 1.
Figure 1. Apparatus for Monitoring of Precipitation (rain, sleet and hail)
Examples of precipitation records are in Figures 2 and 3:
Figure 2. Raindrop Size Distribution
Figure 3. Number of Droplets vs. Time
Instrument Configurations (up to eight probes per monitor)
Rain/Sleet/Hail Monitor Outputs:
Mass flow rate of droplets/pellets (g/m^2 sec) Number of droplets/pellets per m^2/sec
Mass and size distribution of droplets/pellets
Services
Servicing of installed equipment
Field monitoring of droplet/pellet sizes
Installation and introductory testing of a monitor
Development for special applications
