Weather Sensors

Overview

Uncontrollable and unpredictable, weather conditions are central to nearly all environmental monitoring projects. Because of this, weather measuring equipment must be able to withstand the harshest of conditions while consistently producing accurate data. Fondriest Environmental offers a wide range of quality weather sensors that capture even the most detailed aspect of a parameter.

Wind

Wind is the driving force of weather phenomena – sometimes quite literally. It is the vehicle for latent heat moisture that fuels a storm. Wind can provide energy and transfer energy, so an accurate measurement of its speed and direction is a strong predictor of success in an outdoor project. For air pollution, ventilation, extreme weather and wind energy applications, sturdy, reliable wind sensors and anemometers are required. Mechanical wind monitors include a vane with a helicoid propeller that turns a multi-pole magnet. Most are compatible with an array of data loggers. Advanced ultrasound and ultrasonic technology with no moving parts allow easy set-up and provide precise data to measure the unpredictable parameter of wind.

Precipitation

For some monitoring applications, the standard rain collecting gauge does not provide enough detailed information about weather conditions. Since precipitation falls in many forms, more versatile instruments are needed to measure precipitation type and intensity. Tipping rain buckets are a low-cost reliable option for recording rain amount and rainfall rate with simple construction. Research-grade gauges measure amount and intensity and can distinguish among liquid, solid and mixed precipitation. Some sensors use Doppler radar to measure the speed of a falling drop of precipitation. Correlation between drop size and speed provides the precipitation quantity and intensity. With multiple mounting options and weather-proof construction, precipitation instruments are rugged, providing long-lasting measuring capability.

Temperature

Influencing nearly all other weather parameters, temperature is the most commonly measured parameter. Unlike wind and precipitation, temperature is constantly present as an indicator of the kinetic energy of the gases in the air.

Temperature can be measured with a universally-recognized mercury thermometer, thermistors and thermocouples. A thermistor is a temperature-sensitive resistor constructed of a semiconductor in which the resistance decreases with increasing temperature. Thermistors are generally inexpensive and offer a quick response time. Thermocouples are two different metal wires connected at one end. When the wires are heated or cooled, they create a voltage that can be linked to a certain temperature. Thermocouples are ideal for applications that require measurements in a wide range of temperatures.

Humidity

Humidity is a measure of the amount of water vapor in the air. There are a few ways to measure humidity, but relative humidity is the most common method. Relative humidity is measured as a ratio of the amount of water vapor in the air to the total amount of water vapor the air could hold at the current temperature. The higher the humidity, the more heat it absorbs, making an area feel warmer, and often affecting the health of organisms in the area, making it an important weather parameter to measure. Many humidity instruments use capacitance-type sensors. Changes in relative humidity consistently change the shape of the sensor, affecting how it can store an electrical charge. Humidity is often a parameter included in weather stations and temperature meters.

Air Pressure

Directly affecting precipitation, air pressure is the weight of air pressing down on the surface of the earth, over water, land and surface air. When the air is rising over an area, it’s known as low pressure. Alternatively, a high pressure area is one in which air is descending on an area. Precipitation is associated with low pressure because as air rises, it cools, forming condensation that will fall as precipitation if enough water vapor condenses. Often measured by the level of mercury in a barometer, modern pressure measuring devices use a capacitative pressure sensor.

Light

Though only recently harnessed to power buildings and motors, solar energy has been used for millions of years by plants. In both cases, knowing how much light is available is important for energy distribution. Horticulturists and ecologists often measure photosynthetically active radiation (PAR), which is the amount of light available for photosynthesis, falling between the wavelength range of 400 to 700 nanometers. As daylight varies throughout the day, and dissipates at night, PAR levels change. PAR sensors usually measure PAR through Photosynthetic Photon Flux Density (PPFD), a count of the number of protons in PAR range falling on a one meter square area per second. Most light meters and sensors measure PPFD, expressed in millimoles per square meter.