The SKY leaves the factory with pretty good calibration, but calibration can shift during shipping and setup, and will drift over time. Also, your particular installation can affect SKY's calibration (Levelness, stiffness of mount). Fortunately, SKY has a feature that no other weather station in the world has: It learns about your location and produces more accurate data over time. SKY is now going through a continuous learning process that automatically adjusts its calibration as necessary. You probably won't notice anything odd, but rest assured it's only temporary.
All values are reported on a one-minute average cycle. Lightning strikes are instantaneously reported upon detection. The haptic rain sensor also reports instantaneous rain start events when more than 5 seconds of continuous rain occurs. The ultrasonic anemometer samples the wind every 3 seconds and sends an average of wind speed & direction to the Hub.
More on wind sampling...
Every 3 seconds the ultrasonic transducers sample the wind speed and direction. These values are averaged in one-minute observations. The lull is the lowest of the 3-sec readings and the gust is the highest of the 3 sec readings. The one minute averages become part of your station’s long term record. These are World Meteorological Organization (WMO) standard sampling methods.
The ultra-sonic anemometer is comprised of 4 transducers housed in the top of the device. The Tempest measures wind speed and direction based on the time of flight of ultra-sonic pulses between pairs of transducers. This allows for a high degree of accuracy especially in variable wind conditions. For more information, check out Wikipedia on Ultra-Sonic Anemometers.
Tempest uses a patent-pending haptic rain sensor in the top of the device. Using a combination of pressure and capacitance, Tempest measures and counts each falling raindrop. Algorithms exclude things that are not rain (like the rumblings of a passing train or Harley). This allows Tempest to report the instant rain begins falling, the current intensity, and the total rain accumulation over time. Accuracy compares to a large tipping bucket, but does not get fouled with leaves or bird poop.
VERY LIGHT: < 0.25 mm/hour
LIGHT: ≥ 0.25, < 1.0 mm/hour
MODERATE: ≥ 1.0, < 4.0 mm/hour
HEAVY: ≥ 4.0, < 16.0 mm/hour
VERY HEAVY: ≥ 16.0, < 50 mm/hour
EXTREME: > 50.0 mm/hour
Falling/Rising if the magnitude of the pressure change is ≥ 1 hPa
Steady if the magnitude of the pressure change is ≤ 1