Meteorology today 9th edition (chapter 7)
go pilgrimage homeschool 2012
Terms in this set (56)
The growth of a precipitation particle by the collision of an ice crystal or snowflake with a supercooled liquid droplet that freezes upon impact
The clustering together of ice crystals to form snowflakes.
See Ice-crystal process.
A thin sheet of ice that appears relatively dark and may form as supercooled droplets, drizzle, or light rain come in contact with a road surface that is below freezing. Also, thin dark-appearing ice that forms on freshwater or saltwater ponds, or lakes.
A severe weather condition characterized by low temperatures and strong winds (greater than 35 mi/hr) bearing a great amount of snow either falling or blowing. When these conditions continue after the falling snow has ended, it is termed a ground blizzard.
A layer of ice that appears transparent because of its homogeneous structure and small number and size of air pockets.
The introduction of artificial substances (usually silver iodide or dry ice) into a cloud for the purpose of either modifying its development or increasing its precipitation.
Any sudden and heavy rain shower.
The merging of cloud droplets into a single larger droplet.
See Supercooled cloud.
The process of producing precipitation by liquid particles (cloud droplets and raindrops) colliding and joining (coalescing).
The process by which contact with a nucleus such as an ice crystal causes supercooled liquid droplets to change into ice.
In cloud physics, as cloud droplets decrease in size, they exhibit a greater surface curvature that causes a more rapid rate of evaporation.
Tiny particles (ice nuclei) upon which an ice crystal may grow by the process of deposition.
A radar that determines the velocity of falling precipitation either toward or away from the radar unit by taking into account the Doppler shift.
Doppler shift (effect)
The change in the frequency of waves that occurs when the emitter or the observer is moving toward or away from the other.
Small water drops between 0.2 and 0.5 mm in diameter that fall slowly and reduce visibility more than light rain.
In cloud physics, a tiny ice crystal that grows in size and becomes an ice nucleus.
Equilibrium vapor pressure
The necessary vapor pressure around liquid water that allows the water to remain in equilibrium with its environment. Also called saturation vapor pressure.
Falling ice crystals that evaporate before reaching the ground.
Flurries of snow
See Snow flurries.
Particles that promote the freezing of supercooled liquid droplets.
Freezing rain and freezing drizzle
Rain or drizzle that falls in liquid form and then freezes upon striking a cold object or ground. Both can produce a coating of ice on objects which is called glaze.
A cloud or portion of a cloud where only ice crystals exist.
A coating of ice, often clear and smooth, that forms on exposed surfaces by the freezing of a film of supercooled water deposited by rain, drizzle, or fog. As a type of aircraft icing, glaze is called clear ice.
Ice particles between 2 and 5 mm in diameter that form in a cloud often by the process of accretion. Snowflakes that become rounded pellets due to riming are called graupel or snow pellets.
Transparent or partially opaque particles of ice that range in size from that of a pea to that of golf balls.
The accumulation of hail at the earth's surface along a relatively long (10 km), narrow (2 km) band.
Homogeneous (spontaneous) freezing
The freezing of pure water. For tiny cloud droplets, homogeneous freezing does not occur until the air temperature reaches about 40°C.
Particles that act as nuclei for the formation of ice crystals in the atmosphere.
Ice-crystal (Bergeron) process
A process that produces precipitation. The process involves tiny ice crystals in a supercooled cloud growing larger at the expense of the surrounding liquid droplets. Also called the Bergeron process.
A cloud containing both water drops and ice crystals.
Any form of water particles—liquid or solid—that falls from the atmosphere and reaches the ground.
An electronic instrument used to detect objects (such as falling precipitation) by their ability to reflect and scatter microwaves back to a receiver. (See also Doppler radar.)
Precipitation in the form of liquid water drops that have diameters greater than that of drizzle.
An instrument designed to measure the amount of rain that falls during a given time interval.
A white or milky granular deposit of ice formed by the rapid freezing of supercooled water drops as they come in contact with an object in below-freezing air.
Intermittent precipitation from a cumuliform cloud, usually of short duration but often heavy.
A type of precipitation consisting of transparent pellets of ice 5 mm or less in diameter. Same as ice pellets.
A solid form of precipitation composed of ice crystals in complex hexagonal form.
Light showers of snow that fall intermittently.
Precipitation in the form of very small, opaque grains of ice. The solid equivalent of drizzle.
White, opaque, approximately round ice particles between 2 and 5 mm in diameter that form in a cloud either from the sticking together of ice crystals or from the process of accretion. Also called graupel.
Snow squall (shower)
An intermittent heavy shower of snow that greatly reduces visibility.
An aggregate of ice crystals that falls from a cloud.
The dissolving of hygroscopic particles, such as salt, in pure water, thus reducing the relative humidity required for the onset of condensation.
Standard rain gauge
A nonrecording rain gauge with an 8-inch diameter collector funnel and a tube that amplifies rainfall by tenfold.
Supercooled cloud (or cloud droplets)
A cloud composed of liquid droplets at temperatures below 0°C (32°F). When the cloud is on the ground it is called supercooled fog or cold fog.
The constant speed obtained by a falling object when the upward drag on the object balances the downward force of gravity.
Tipping bucket rain gauge
A rain gauge that records rainfall by collecting rain in a chamber (bucket) that tips when the chamber fills with 0.01 in. (0.025 cm) of rain.
Trace (of precipitation)
An amount of precipitation less than 0.01 in. in. (0.025 cm).
Precipitation that falls from a cloud but evaporates before reaching the ground. (See Fall streaks.)
The depth of water that would result from the melting of a snow sample. Typically about 10 inches of snow will melt to 1 inch of water, producing a water equivalent of 10 to 1.
Weighing rain gauge
A rain gauge that records rainfall by weighing the collected water over a given time and converting the amount of water to rainfall depth.