Skywatch

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Tour of the weather station.

Here is a tour of my weather station and it's components.

This is the weather station. On the top of the station is the anemometer which measures the wind speed and wind vane which monitors wind direction. On the side are the UV and solar sensors. This measures the sunlight. Below this is the anemometer's interface. This allows the NRG wind sensors to be compatible with the station. On the side of this is the weather cam enclosure. This is a wireless camera system which has a receiver that plugs into the computer. The computer feeds the images to Wunderground. On the lower part of the pole is the rain/temperature/humidity with transmitter. All the weather instruments with the exception of the camera and wind sensors are part of a Davis Wireless Vantage Pro2 Plus. The camera is a GE wireless.

 

Solar and UV (sunlight)

This is the UV and solar apparatus. This monitors and records the sunlight activity such as intensity, and duration of sunlight. The solar radiation sensor (pyranometer) measures the infrared and visible light part of the solar spectrum (300-1100 nm) while the UV sensor measures the ultraviolet spectrum (290-390nm). This is the component of the sun that causes sunburns.  

Weather Display software program also uses the solar data to monitor cloud cover. Weather Display uses the longitude, latitude, elevation, and time of year to determine the maximum possible solar value for location. Then compares the current solar reading with this maximum value to come up with a solar % (percentage) This is used to determine the cloud cover and sky conditions. On a clear and sunny day the solar percentage is near 100%. and on a cloudy day it's near 0-10% and everything in between. 30-50% indicates broken sky or more clouds than sun. 51-65% indicates partly cloudy or more sun than clouds. 66%-74% indicates few clouds like the puff ball clouds on hot summer days. 75% and higher indicate a sunny clear sky. This is also the threshold at which the sunshine hours are counted.

Here's a scale to simplify. The abbreviations are those used by the NWS FAA and WMO

0-10 % = cloudy or overcast (OVC)
11-35 % = mostly cloudy or broken  (BKN)
36-50%= half and half or partly cloudy (SCT)
50-74%= mostly sunny (FEW)
75%+= clear sky (CLR)

The letter abbreviations are displayed on Wunderground in the tabular display and also on the WunderMap data display when you click on my station.

Wind speed and direction

Here are the wind components. This includes a cup anemometer on the right and wind vane on the left. These sensors are NIST calibrated, certified, and considered industry standard equipment for meteorological and wind research applications but can be suited for weather stations such as this. The Anemometer is a generator type which consists of a magnet and copper coil. The magnet induces an electrical current into the coil. This is an AC square wave output where the frequency  in Hertz (Hz) is dependant on the wind then converted into a simple on/off pulse through an interface module that is then connected to the transmitter.

   The wind direction vane is a potentiometer type vane that changes it's resistance as the vane rotates. This allows for 1 degree resolution. This also connects to the transmitter through the interface. Sensors are located 26' above ground level and sited with respect to surrounding obstructions resulting in better wind accuracy with minimal influence by nearby obstacles.

Weather camera

Here is the camera. The camera is a GE wireless camera. The camera isn't designed for being outdoors however I built a homemade enclosure out of old Tupperware containers and sealed the camera inside the enclosure. The rear of the enclosure I cut open a hole for a fan to help keep the camera cool on hot summer days. A draft tube is installed over the fan to keep rain out protecting the camera. The only drawback is the enclosure inhibits the infrared so the night vision is useless. Sometime at a later date I may install an external infrared night vision unit but for now this will do. This camera is focused south to catch any weather and storm activity to the south.

Not pictured but I have a 2nd web cam hooked up aimed north. For this I use a Logitech C510. Attached to the interior of a window. I may also add an infrared light for it too. 

2 cameras give me more coverage of what ever comes through. North and South seem to be where most of our storms come from so for this I have them aimed in these directions.

Rainfall, Temperature, Humidity, and transmitter

This is the rain/temperature/humidity unit. The black object on top is the rain gauge. This uses an 8" NWS standard funnel. Laser calibrated and installed level for accuracy. Under this is the temperature and humidity. The pagoda looking thing is a solar radiation shield and keeps the sun and solar heating away from the sensors and allows for natural ventilation resulting in the actual measurement of the air with minimal influence from other factors. On the front is the transmitter. All the sensors plug into this. This is solar powered with a 3 way power supply in any condition be it cloudy, snowy, icy or anything that causes long periods of time without the sun this will keep working.

Leaf wetness

 Here is the leaf wetness sensor. Another component of my weather station. These help determine surface wetness of leaves and the duration they stay wet to gauge the risk of disease, fungus, and insect infestations on vegetables. The sensor uses gold plated contacts arranged in interlocking fingers. When moisture is present this bridges the contacts and changes the resistance across the sensor. This is read on a scale from 0-15. 0 = dry 15 = wet.

Apart from determining leaf wetness for plant disease control, this sensor also functions as a rainfall detector. While the rain gauge measures rainfall totals this sensor is useful in determining approximately when the rain started. Or days where we get a trace of rain. This monitors even the lightest rain activity. So even if the rain's not enough to be measured by the rain gauge, this sensor will measure it.

The sensor can also detect fog and dew. In determining what's fog/dew and what's rain the dew point and temperature should be compared along with the leaf wetness. If the dew point temperature is at or close to the actual temperature the readings are caused by fog and dew. If the dew point is considerably different than the actual temperature this would most likely indicate rain. Another way to tell the difference between dew/fog and rain is how quickly the readings go up. In the case of rain the readings will instantly go from 0-15. In the case of dew and fog and condensation the readings will gradually go up.

Soil temperature and moisture.

Here are the soil sensors. I have 2 of these pairs. Each pair monitors the temperature and moisture. The pairs are buried at different depths. 9" and 20".

The temperature sensor uses a resistance type wire concealed in a stainless steel capsule and conducts the soil's temperature. This protects the sensors from the corrosive properties of soil and allows the sensors to accurately measure temperature.

The moisture sensor uses two electrodes embedded in a cylinder or nugget of gypsum that protects the sensor while allowing the moisture to be measured. The gypsum nugget is then wrapped in a sheet of wool then encased in a perforated steel casing. These sensors are used by the Davis Vantage Pro2 and sold by Davis but are known as Watermark sensors manufactured by Irrometer.

Moisture readings are measured in a unit called centibars and works in reverse to how moisture is normally read. The scale goes from 0-200cb. And unlike common moisture meters, the higher the number the drier the soil. So 0 centibars is completely saturated soil while 200 centibars is bone dry.  
Here is the receiver/console of the Vantage Pro2 weather station. This monitors and graphs all the weather data. The console also contains the barometer. With this along with the outdoor sensors, the console also comes up with the forecast. The console then connects to the computer through a WeatherLink data logger and PC connection.
This is Weather Display Version 10.37 build 70. This runs my whole weather station. Creates all sorts of graphs, charts, and cool stuff. This does a great job of managing the station and data. This uploads data to Wunderground CWOP PWS Weather Weather Bug Twitter Anything Weather and AWEKAS. Really fun to use and I highly recommend it.
Here is a live data feed from Wunderground.