Glossary of Weather Terms: Top 50 You Should Know

A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z

We’re excited to present our glossary of weather terms, perfect for anyone interested in home weather stations or weather hobbies! Whether you’re just starting out or have some experience, this guide will give you a thorough understanding of the language used in weather forecasting. Below are the top 50 weather terms you should know.

 

A

 

ABSOLUTE HUMIDITY – The mass of water vapor per unit volume of air, usually measured in grams per cubic meter.

ALTIMETER – An instrument that measures altitude above sea level by measuring air pressure.

ANEMOMETER – An anemometer is an instrument which measures wind speed.

ANTICYCLONE – A weather system characterized by high atmospheric pressure, generally associated with clear skies and calm conditions.

ATMOSPHERE – The layer of gases that surround the Earth, composed primarily of nitrogen (78%) and oxygen (21%).

ATMOSPHERIC PRESSURE – The force exerted by the weight of the atmosphere on the Earth’s surface, measured in units such as millibars or inches of mercury.

 

B

 

BAROMETER – A barometer is an instrument used to measure atmospheric pressure. Two examples are the aneroid barometer and the mercurial barometer.

BAROMETRIC PRESSURE – Barometric pressure is the pressure exerted by the atmosphere at a given point. Using a barometer, it’s measurement can be expressed in several ways. One is in millibars. Another is in inches or millimeters of mercury (Hg). Also known as atmospheric pressure.

 

 

C

 

CELSIUS – A unit of measurement for temperature on the Celsius scale, where water freezes at 0 degrees and boils at 100 degrees at standard atmospheric pressure.

CIRRUS CLOUDS – High, wispy clouds made up of ice crystals that are typically found at altitudes of 20,000 feet or higher.

CLIMATE – The long-term average weather conditions in a particular region or location.

COLD FRONT – A boundary between two air masses where a colder, denser air mass replaces a warmer air mass, often resulting in precipitation.

CONDENSATION – The process by which water vapor in the air is converted into liquid water, usually by cooling the air or increasing its pressure.

CUMULONIMBUS CLOUDS – Large, dense clouds that are capable of producing thunderstorms, lightning, and heavy precipitation.

CUMULUS CLOUDS – Puffy, white clouds often resemble cotton balls and are typically found at lower altitudes.

CYCLONE – A weather system characterized by low atmospheric pressure, generally associated with cloudy skies, precipitation, and wind.

 

D

 

DEW POINT – The temperature to which air must be cooled to reach saturation (100% relative humidity) and for dew or frost to form.

DOPPLER RADAR – A type of radar that uses the Doppler effect to measure the speed and direction of moving objects, such as rain or snow particles in the atmosphere.

DROUGHT – A prolonged period of abnormally low rainfall or precipitation, often resulting in water shortages.

 

E

 

EVAPORATION – The process by which liquid water is converted into water vapor, usually by heating the water or increasing its surface area.

EVAPOTRANSPIRATION – The process by which water is transferred from the land to the atmosphere by evaporation from the soil and transpiration from plants.

 

F

 

FLASH FLOOD – A sudden and rapid flooding of low-lying areas due to heavy rainfall, often occurring in urban areas or near rivers and streams.

FOG – A cloud that forms at or near the ground when the air is cooled to its dew point.

FRONT – A boundary between two air masses that have different characteristics, such as temperature or humidity.

 

G

 

GRAVITY – a natural force that causes objects with mass to attract each other. The strength of gravity depends on the mass of the objects and the distance between them.

 

H

 

HAIL – Precipitation in the form of balls or lumps of ice that are usually larger than 5 millimeters in diameter.

HEAT INDEX – A measure of the human discomfort caused by the combined effect of high temperature and high relative humidity.

HIGH PRESSURE SYSTEM – A weather system characterized by high atmospheric pressure, generally associated with clear skies and calm conditions.

HUMIDITY – Humidity is the amount of water vapor in the air. It is often confused with relative humidity or dew point. Types of humidity include absolute humidity, relative humidity, and specific humidity.

HURRICANE – A large, rotating storm that forms over tropical waters and can cause high winds, heavy rain, storm surges, and flooding.

HYGROMETER – A hygrometer is an instrument that measures the water vapor content of the atmosphere.

 

I

 

INCHES OF MERCURY (HG) – The name comes from the use of mercurial barometers which equate the height of a column of mercury with air pressure. One inch of mercury is equivalent to 33.86 millibars or 25.40 millimeters. (See barometric pressure.) First devised in 1644 by Evangelista Torricelli (1608-1647), an Italian physicist and mathematician, to explain the fundamental principles of hydromechanics.

INFRARED RADIATION – Electromagnetic radiation that has a longer wavelength than visible light and can be felt as heat.

 

J

 

JET STREAM – A narrow band of strong, high-altitude winds that circle the Earth, often affecting weather patterns and air travel.

 

K

KNOT – A knot is a nautical unit of speed equal to the velocity at which one nautical mile is traveled in one hour. Used primarily by marine interests and in weather observations. A knot is equivalent to 1.151 miles per hour or 1.852 kilometers per hour.

 

L

 

LOW PRESSURE SYSTEM – A weather system characterized by low atmospheric pressure, generally associated with cloudy skies, precipitation, and wind.

 

M

 

MERCURIAL BAROMETER – A mercurial barometer is an instrument used for measuring the change in atmospheric pressure. It uses a long glass tube, open at one end and closed at the other. After first filling the open end with mercury, it is then temporarily sealed and placed into a cistern of mercury. A nearly perfect vacuum is established at the closed end after the mercury descends. The height of the column of mercury in the tube is a measurement of air pressure. As atmospheric pressure increases, the mercury is forced from the cistern up the tube; when the atmospheric pressure decreases, the mercury flows back into the cistern. Measurement is taken in inches of mercury. Although mercurial barometers are very accurate, practicality has led observers to use aneroid barometers. First used by Evangelista Torricelli (1608-1647), an Italian physicist and mathematician, to explain the fundamental principles of hydromechanics.

METEOROLOGY/METEOROLOGIST – Meteorology is the science and study of the atmosphere and atmospheric phenomena. Various areas of meteorology include agricultural, applied, astrometerology, aviation, dynamic, hydrometeorology, operational, and synoptic, to name a few. A scientist who studies the atmosphere and atmospheric phenomena is known as a Meteorologist.

MICROBURST – A sudden and intense downdraft of air that can cause strong winds and damage at the surface.

MOISTURE – Moisture refers to the water vapor content in the atmosphere, or the total water, liquid, solid or vapor, in a given volume of air.

 

N

 

NOR’EASTER – A Nor’Easter is a cyclonic storm occurring off the east coast of North America. These winter weather events are notorious for producing heavy snow, rain, and tremendous waves that crash onto Atlantic beaches, often causing beach erosion and structural damage. Wind gusts associated with these storms can exceed hurricane force in intensity. A Nor’easter gets its name from the continuously strong northeasterly winds blowing in from the ocean ahead of the storm and over the coastal areas.

 

O

 

OZONE – A molecule composed of three oxygen atoms bonded together. It is a form of oxygen that is present in our atmosphere and helps to protect us from harmful ultraviolet radiation from the sun.

 

P

 

PRECIPITATION – Precipitation is any and all forms of water, liquid or solid, that falls from clouds and reaches the ground. This includes drizzle, freezing drizzle, freezing rain, hail, ice crystals, ice pellets, rain, snow, snow pellets, and snow grains. The amount of fall is usually expressed in inches of liquid water depth of the substance that has fallen at a given point over a specified time period.

PSYCHROMETER – A type of hygrometer that uses two thermometers, one wet-bulb, and one dry bulb, to measure relative humidity.

 

Q

 

QPF – Quantitative Precipitation Forecast

 

R

 

RADIOSONDE – An instrument package that is carried aloft by a balloon to measure temperature, pressure, and relative humidity.

RAIN – Rain is precipitation in the form of liquid water droplets greater than 0.5 mm. If widely scattered, the drop size may be smaller. It is reported as “R” in an observation and on the METAR. The intensity of rain is based on rate of fall. “Very light” (R–) means that the scattered drops do not completely wet a surface. “Light” (R-) means it is greater than a trace and up to 0.10 inch per hour. “Moderate” (R) means the rate of fall is between 0.11 to 0.30 inch per hour. “Heavy” (R+) means over 0.30 inch per hour.

RAIN GAUGE – A rain gauge is a device for collecting and measuring the amount of rain which falls.

RELATIVE HUMIDITY – A type of humidity that considers the ratio of the actual vapor pressure of the air to the saturation vapor pressure. Using a humidity instrument to measure proper relative humidity could be useful at home since the lack of moisture could impact wood causing shrinking and cracking to your floors and furniture.

 

S

 

SOLAR RADIATION – Electromagnetic radiation from the sun, including visible light, ultraviolet light, and infrared radiation.

 

T

 

TEMPERATURE – Temperature is the measure of molecular motion or the degree of heat of a substance. It is measured on an arbitrary scale from absolute zero, where the molecules theoretically stop moving. It is also the degree of hotness or coldness. In surface observations, it refers primarily to the free air or ambient temperature close to the surface of the earth.

THERMOMETER – A thermometer is an instrument used for measuring temperature. The different scales used in meteorology are Celsius, Fahrenheit, and Kelvin or Absolute.

TIDE – The tide is the periodic rising and falling of the earth’s oceans and atmosphere. It is the result of the tide-producing forces of the moon and the sun acting on the rotating earth. This propagates a wave through the atmosphere and along the surface of the earth’s waters.

TIDE CLOCK – A tide clock is a specially designed clock that keeps track of the Moon’s apparent motion around the Earth. Along many coastlines, the Moon contributes the major part (67%) of the combined lunar and solar tides. The exact interval between tides is influenced by the position of the Moon and Sun relative to the Earth, as well as the specific location on Earth where the tide is being measured.

 

U

 

UV INDEX – A measure of the strength of ultraviolet radiation from the sun, with higher values indicating a greater risk of sunburn and skin damage.

 

V

 

VIRGA – A meteorological phenomenon where rain falls from clouds but evaporates before it reaches the ground.

 

W

 

WEATHER STATION – A weather station is a device that collects data related to the weather and environment using many different sensors. Weather stations are also called weather centers, personal weather stations, professional weather stations, home weather stations, weather forecasters and forecasters. Weather stations sensors may include a thermometer to take temperature readings, a barometer to measure the pressure in the atmosphere,  wind instruments, as well as other sensors to measure rain, wind, humidity and more. Weather stations range from simple analog technology to digital technology. Some even connect to your computer or the internet, so the data collected can be analyzed using weather station software.

WIND CHILL – A measure of how cold it feels outside when wind is taken into account, based on the rate of heat loss from exposed skin due to the combined effect of wind and cold air temperature.

WIND SPEED – Wind speed is the rate of the motion of the air on a unit of time. It can be measured in a number of ways including, mph (Mile per Hour), m/s (Meters per Second), ft/m (Feet per Minute), km/h (Kilometers per Hour), kt (Knots) and B (Beaufort Force).

 

X

 

X-BAND – A frequency range used in radar systems and communication technology, typically ranging from 8 to 12 gigahertz.

 

Y

 

Z

 

ZFP – Zone Forecast Product. A forecast product that provides information on expected sky conditions, precipitation, visibility, temperature, wind direction, and speed for various zone groups every 12 hours for up to 7 days.