On-farm weather stations are agricultural machines that measure local conditions directly in a field. They matter because weather can change over short distances, so data from a distant airport or city station may not match what crops actually experience. A station with an anemometer, wind vane, rain gauge, thermometer, humidity sensor, and soil sensors helps farmers make faster and more accurate decisions.
These measurements support irrigation scheduling, spray timing, frost protection, and disease risk warnings.
Key Facts
- Wind speed is measured by an anemometer, often in m/s or km/h.
- Wind direction is measured by a wind vane and reported as the direction the wind comes from.
- Rainfall depth can be calculated as precipitation depth = collected water volume / collection area.
- Relative humidity compares the actual water vapor in air to the maximum possible at that temperature.
- Evapotranspiration estimates crop water loss from soil evaporation plus plant transpiration.
- Good sensor placement requires open airflow, level mounting, and distance from buildings, trees, and irrigation spray.
Vocabulary
- Anemometer
- An anemometer is a sensor that measures wind speed, often using rotating cups or ultrasonic signals.
- Wind vane
- A wind vane is a sensor that points into the wind to show the direction the wind is coming from.
- Rain gauge
- A rain gauge is an instrument that collects precipitation so rainfall depth can be measured.
- Relative humidity
- Relative humidity is the percentage of water vapor in the air compared with the maximum amount the air can hold at that temperature.
- Evapotranspiration
- Evapotranspiration is the combined loss of water from soil evaporation and plant transpiration.
Common Mistakes to Avoid
- Placing the weather station next to a building or tree is wrong because wind, temperature, and rainfall readings can be blocked or distorted.
- Reading wind direction as where the wind is going is wrong because wind direction is named for where the wind comes from.
- Using one rainfall measurement for an entire farm can be wrong because storms may be uneven, especially across large or hilly fields.
- Ignoring sensor calibration is wrong because small measurement errors can lead to poor irrigation, spraying, or frost-protection decisions.
Practice Questions
- 1 A rain gauge has a collection area of 200 cm2 and collects 300 cm3 of water during a storm. What was the rainfall depth in cm?
- 2 An anemometer records wind speeds of 4 m/s, 6 m/s, 5 m/s, and 7 m/s over four equal time intervals. What is the average wind speed?
- 3 A farmer plans to spray pesticide, but the on-farm station reports high wind speed and wind blowing toward a neighboring field. Explain why delaying spraying may be the best decision.