WELCOME TO CRONDALL WEATHER

Supplying live weather data and related weather statistics for Crondall since 2006

Crondall Weather

Although we primarily service Crondall and the surrounding areas, we are actually visited from all over the world.  Here’s the latest map:

Locations of Site Visitors

This website provides an ever changing source of weather information for Crondall, Farnham, Aldershot, Fleet and the surrounding areas.

The weather data is freely supplied and presented in various formats – drop us a note if you have a special need.

As well as providing general interest weather and updates for the local residents and gardeners, is also used :

  • an official local Weather station for the Met Office

  • to help local residents with support for weather related insurance claims

  • to help the Hampshire Ornithological society understand migratory patterns

  • to help understand the effect of weather patterns on the grazing patterns of cattle on Ash ranges

  • to provide detailed rainfall statistics to help various organisations with Flood prevention and planning

The raw live weather is supplied by a Davis Vantage Pro2 weather system, which is acknowledged as being one of the World’s leading systems (full specification in the tabs below).

The site went live towards the end of January 2006.

A Few Statistics

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Countries Visiting
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Weather Alert Sign Ups
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Weather Records in Database (end June 2020)

Weather Equipment Used to Collect Data

Crondall Weather anemometer
The anemometer is mounted above the roof line to give an unimpeded measurement of the wind.

Thankfully Robert Hill, chimney sweep extraordinaire (01252 – 621031), was available to properly orient and secure the securing brackets.

RainCollector

The rainfall collector and temperature / humidity / pressure measuring system is properly shielded and sited away from any major structures.

The reading should therefore be very accurate (although no guarantees or warranties can of course be given).  

Solar Sensor

The Solar sensor easures solar radiation in Watts per square metre.

This also allows (along with the anemometer and temperature/humidity sensor) us to monitor evapotranspiration to give a sense of how much water plants are needing each day.

The diffuser element and housing are carefully designed for accurate cosine response. Silicon photo diode provides good match to solar spectrum.

The two-piece housing minimizes radiation heating, allows convection cooling of the sensor, and prevents the trapping of water or dust.

Boltek Lightning Detector

We’re planning on adding a Crondall based live lightning tracker later this year – at the moment we have to “borrow” the data.

Accuracy of Data

Temperature

Outside Temperature
Range. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -40° to +150°F (-40° to +65°C)
Sensor Accuracy . . . . . . . . . . . . . . . . . . . . . . . . . . . ±0.5°F (±0.3°C)
Radiation Induced Error (Passive Shield) . . . . . . . . . +4°F (2°C) at solar noon (insolation = 1040 W/m2, avg. wind speed  2 mph (1 ms)) (reference: RM Young Model 43408 Fan-Aspirated Radiation Shield)
Update Interval . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 to 12 seconds

Humidity

Outside Relative Humidity (sensor located in ISS)
Resolution and Units. . . . . . . . . . . . . . . . . . . . . . . . . 1%
Range. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 to 100% RH
Accuracy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ±2%
Drift . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . <0.25% per year
Update Interval . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 seconds to 1 minute

Rainfall

Resolution and Units. . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.2 mm
Daily/Storm Rainfall Range . . . . . . . . . . . . . . . . . . . . . . . 0 to 99.99″ (0 to 999.8 mm)
Monthly/Yearly/Total Rainfall Range . . . . . . . . . . . . . . . . 0 to 199.99″ (0 to 6553 mm)
Accuracy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . For rain rates up to 10″/hr (250 mm/hr): ±3% of total or ± one tip of the spoon (0.01″/0.2mm), whichever is greater.
Update Interval . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 to 24 seconds
Storm Determination Method . . . . . . . . . . . . . . . . . . . . . 0.02″ (0.4 mm) begins a storm event, 24 hours without further accumulation ends a storm event
Rain Rate
Resolution and Units. . . . . . . . . . . . . . . . . . . . . . . . . . . .  0.1 mm
Range. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0, 0.04″/hr (1 mm/hr) to 30″/hr (0 to 762 mm/hr)
Accuracy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ±5% for rain rates up to 10″/hr (250 mm/hr)
Update Interval . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 to 24 seconds
Calculation Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Measures time between successive tips of tipping spoon. Elapsed time greater than 15 minutes or only one tip of the rain collector constitutes a rain rate of zero.

Barometer

Resolution and Units. . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.01″ Hg, 0.1 mm Hg, 0.1 hPa/mb (user-selectable)
Range. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16.00″ to 32.50″ Hg, 410 to 820 mm Hg, 540 to 1100 hPa/mb
Uncorrected Reading Accuracy. . . . . . . . . . . . . . . . . . . . ±0.03″ Hg (±0.8 mm Hg, ±1.0 hPa/mb) (at room temperature)
Sea-Level Reduction Equation Used. . . . . . . . . . . . . . . . United States Method employed prior to use of current “R Factor” method
Equation Source . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Smithsonian Meteorological Tables
Equation Accuracy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ±0.01″ Hg (±0.3 mm Hg, ±0.3 hPa/mb)
Elevation Accuracy Required . . . . . . . . . . . . . . . . . . . . . ±10’ (3m) to meet equation accuracy specification
Overall Accuracy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ±0.03″ Hg (±0.8 mm Hg, ±1.0 hPa/mb)
Trend (change in 3 hours). . . . . . . . . . . . . . . . . . . . . . . . Change 0.06″ (2 hPa/mb,1.5 mm Hg) = Rapidly Change 0.02″ (0.7hPa/mb, 0.5 mm Hg)= Slowly
Trend Indication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 position arrow: Rising (rapidly or slowly), Steady, or Falling (rapidly or slowly)
Update Interval . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 minute or when console BAR key is pressed twice

Wind

Wind Chill (Calculated)
Resolution and Units. . . . . . . . . . . . . . . . . . . . . . . . . 1°F or 1°C (user-selectable) °C is converted from °F rounded to the nearest 1°C
Range. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -110° to +135°F (-79° to +57°C)
Accuracy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ±2°F (±1°C) (typical)
Update Interval . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 to 12 seconds
Source . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . United States National Weather Service (NWS)/NOAA
Equation Used . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Osczevski (1995) (adopted by US NWS in 2001)
Variables Used . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Instant Outside Temperature and 10-min. Avg. Wind Speed
Wind Direction
Range. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 – 360°
Display Resolution . . . . . . . . . . . . . . . . . . . . . . . . . . 16 points (22.5°) on compass rose, 1° in numeric display
Accuracy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ±3°
Update Interval . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.5 to 3 seconds
Wind Speed
Resolution and Units. . . . . . . . . . . . . . . . . . . . . . . . . 1 mph
Range. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0 to 200 mph, 0 to 173 knots, 0 to 89 m/s, 0 to 322 km/h
Update Interval . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Instant Reading: 2.5 to 3 seconds, 10-minute Average: 1 minute
Accuracy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ±2 mph (2 kts, 3.2 km/h, 0.9 m/s) or ±5%, whichever is greater

Solar

Resolution and Units . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 W/m2
Range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0 to 1800 W/m2
Accuracy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ±5% of full scale (Reference: Eppley PSP at 1000 W/m2)
Drift . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . up to ±2% per year
Cosine Response. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ±3% for angle of incidence from 0° to 75°
Temperature Coefficient. . . . . . . . . . . . . . . . . . . . . . . . . . -0.067% per °F (-0.12% per °C); reference temperature = 77°F (25 °C)
Update Interval . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 seconds to 1 minute (5 minutes when dark)