Glossary of Weather Station Terms

Anemometer - An anemometer measures wind speed. The term comes from the Greek word, anemos, which means wind. There are 2 types of anemometers: those which measure wind velocity and those which measure wind pressure. However since wind velocity and pressure are so closely connected a good quality anemometer of either type will give accurate measurements of either quantity.

Barometer - A barometer measures atmospheric pressure. It uses mercury, air, or water to measure the pressure exerted by the atmosphere. A barometer can forecast upcoming weather based on changes in the atmospheric pressure.

Dew Point - The temperature at which water vapor in the air becomes saturated and condenses into water or dew - also referred to as dewpoint. When the dew point falls below freezing it is referred to as frost point.

EAS - EAS is short for the Emergency Alert System. This is a broadcast of national and local government emergency alerts of issues affecting public health and safety. These can consist of weather emergencies like tornados and earthquakes, toxic chemical spills and other emergencies that require public notification.

Evapotranspiration - The process whereby moisture is returned to the air through evaporation from the soil and transpiration by plants. Transpiration is the emission of water vapor from the leaves of plants.

Heat Index - An index that combines the relative humidity level and air temperature in order to find the equivalent temperature in terms of human perception. Basically how hot it feels to you based on the two criteria.

Hygrometer - A hygrometer measures relative humidity. Relative humidity is the quantity or percentage of water vapor (water in gas form) in the air.

Leaf Wetness Sensor - A leaf wetness sensor detects water on the surface of a leaf. It does this by measuring the electrical resistance of water on the surface of the leaf or foliage. Leaf wetness sensors measure from 0 (completely dry) to 15 (saturated).

NOAA - NOAA or N.O.A.A. is short for the National Oceanic and Atmospheric Administration. The NOAA broadcasts emergency alerts, weather forecasts, travel conditions and storm warnings around the clock.

Rain Gauge - A rain gauge measures rain or liquid precipitation over a period of time. A rain gauge does not meaasure solid precipitation or snow, this would be measured with a snow gauge.

SAME - SAME or S.A.M.E. is short for Specific Area Message Encoding. A radio equipped with SAME technology will receive all NOAA and EAS broadcasts.

Snow Gauge - A snow gauge measures the quantity of solid precipitation or snow over a period of time.

Soil Moisture Sensor - A soil moisture sensor measures the amount of moisture or water in the soil.

Soil Temperature Sensor - A soil temperature sensor measures the temperature of the soil.

Solar Radiation Sensor - A solar radiation sensor measures the amount of solar energy radiating from the sun.

Thermometer - A thermometer measures temperature. The term thermometer comes from 2 words: the Greek word, thermo, which means heat and the Greek word meter, which means to measure.

Ultraviolet Sensor - An ultraviolet or UV sensor measures the amount of ultraviolet light radiating from the sun.

Water Temperature Sensor - A water temperature sensor measures the temperature of water or another liquid.

Wind Chill - The apparent temperature that a human perceives based on a combination of temperature and wind speed. This measurement is based on the fact that wind can make the air significantly colder.

Wind Vane - A wind vane or weather vane is an instrument which measures wind direction. A wind vane is usually used in conjunction with an anemometer.