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clouds

Terms in this set (56)

Calorie
The calorie (symbolized cal) is a unit of heat occasionally used in the centimeter-gram-second ( cgs ) system of physical units.
Latent Heat
the heat required to convert a solid into a liquid or vapor, or a liquid into a vapor, without change of temperature.
Evaporation
Evaporation is the process of a substance in a liquid state changing to a gaseous state due to an increase in temperature and/or pressure. Evaporation is a fundamental part of the water cycle and is constantly occurring throughout nature.
Condensation
water that collects as droplets on a cold surface when humid air is in contact with it.
Sublimation
Sublimation is a chemical process where a solid turns into a gas without going through a liquid stage. An example of sublimiation is when ice cubes shrink in the freezer.
Deposition
Deposition is the geological process in which sediments, soil and rocks are added to a landform or land mass. Wind, ice, and water, as well as sediment flowing via gravity, transport previously eroded sediment, which, at the loss of enough kinetic energy in the fluid, is deposited, building up layers of sediment.
Humidity
a quantity representing the amount of water vapor in the atmosphere or a gas.
Saturation
the degree or extent to which something is dissolved or absorbed compared with the maximum possible, usually expressed as a percentage.
Vapor Pressure
the pressure of a vapor in contact with its liquid or solid form.
Mixing Ratio
In atmospheric chemistry, mixing ratio usually refers to the mole ratio , which is defined as the amount of a constituent divided by the total amount of all other constituents in a mixture: The mole ratio is also called amount ratio.
Relative Humidity
the amount of water vapor present in air expressed as a percentage of the amount needed for saturation at the same temperature.
Dew-point Temperature
Dew point temperature is defined as the temperature to which the air would have to cool (at constant pressure and constant water vapor content) in order to reach saturation. A state of saturation exists when the air is holding the maximum amount of water vapor possible at the existing temperature and pressure.
Hygrometer
an instrument for measuring the humidity of the air or a gas.
Psychrometer
a hygrometer consisting of a wet-bulb and a dry-bulb thermometer, the difference in the two thermometer readings being used to determine atmospheric humidity.
Adiabatic Temperature Changes
When the pressure applied on a parcel of air is reduced, the air in the parcel is allowed to expand; as the volume increases, the temperature falls as its internal energy decreases. Adiabatic cooling occurs in the Earth's atmosphere with orographic lifting and lee waves, and this can form pileus or lenticular clouds.
Parcel
an object, article, container, or quantity of something wrapped or packed up; small package; bundle.
Dry Adiabatic Rate
The dry adiabatic lapse rate (DALR) is the rate of temperature decrease with altitude for a parcel of dry or unsaturated air rising under adiabatic conditions. Unsaturated air has less than 100% relative humidity; i.e. its actual temperature is higher than its dew point.
Wet Adiabatic Rate
Dry air cools at about 10 C/km (the 'dry adiabatic lapse rate'), while moist air usually cools at less than 6 C/km ('moist adiabatic lapse rate'). The word adiabatic means that no outside heat is involved in the warming or cooling of the air parcels.
Orographic Lifting
Orographic lift occurs when an air mass is forced from a low elevation to a higher elevation as it moves over rising terrain. As the air mass gains altitude it quickly cools down adiabatically, which can raise the relative humidity to 100% and create clouds and, under the right conditions, precipitation.
Rain Shadow Desert
A rain shadow is a patch of land that has been forced to become a desert because mountain ranges blocked all plant-growing, rainy weather. On one side of the mountain, wet weather systems drop rain and snow. On the other side of the mountain—the rain shadow side—all that precipitation is blocked.
Front
A weather front is the area where two air masses with different temperatures and densities collide, but do not mix. The collision often causes storms and changeable weather. There are four types of fronts: cold fronts, warm fronts, stationary fronts, and occluded fronts.
Frontal Wedging
Lifting also occurs along frontal boundaries, which separate air masses of different density. In the case of a cold front, a colder, denser air mass lifts the warm, moist air ahead of it. As the air rises, it cools and its moisture condenses to produce clouds and precipitation.
Convergence
a location where airflows or ocean currents meet, characteristically marked by upwelling (of air) or downwelling (of water).
Localized Convective Lifting
Lifting by Convection: upward moving thermals. In meteorology, convection refers primarily to atmospheric motions in the vertical direction. As the earth is heated by the sun, bubbles of hot air (called thermals) rise upward from the warm surface.
Stable Air
This is referred to as stable air. If a rising parcel of air is warmer than the surrounding atmosphere it will continue to rise. This is because warm air is less dense or lighter than cool air. This is referred to as unstable air.
Unstable Air
To be "unstable", the lowest layers of an air mass must be so warm and/or humid that, if some of the air rises, then that air parcel is warmer than its environment, and so it continues to rise. This is called moist convection.
Absolute Stability
Definition � Absolute Stability. A numerical method is said to be absolutely stable for a given if all the roots of lie within the unit circle. A region of the complex plane is said to be a region of absolute stability if the method is stable for all in .
Absolute Instability
is the state in which an air parcel finds itself warmer than the air surrounding it at the same pressure (elevation). The air parcel is buoyant. It will spontaneously rise. (If moisture is condensing, the resulting cloud will be cumulus, cumulus congestus or cumulonimbus (associated with thunderstorms)).
Conditional Instability
conditional instability. The state of a layer of unsaturated air when its lapse rate of temperature is less than the dry-adiabatic lapse rate but greater than the moist-adiabatic lapse rate.
Condensation Nuclei
Cloud condensation nuclei or CCNs (also known as cloud seeds) are small particles typically 0.2 µm, or 1/100th the size of a cloud droplet on which water vapour condenses. Water requires a non-gaseous surface to make the transition from a vapour to a liquid; this process is called condensation.
Hygroscopic Nuclei
These nuclei are 'hygroscopic' meaning they attract water molecules. Called "cloud condensation nuclei", these water molecule attracting particles are about 1/100th the size of a cloud droplet upon which water condenses.
Clouds
a visible mass of condensed water vapor floating in the atmosphere, typically high above the ground.
Cirrus
cloud forming wispy filamentous tufted streaks ("mare's tails") at high altitude, usually 16,500-45,000 feet (5-13 km).
Cumulus
Cumulus clouds are puffy clouds that sometimes look like pieces of floating cotton. The base of each cloud is often flat and may be only 1000 meters (3300 feet) above the ground. The top of the cloud has rounded towers.
Stratus
Stratus clouds are low-level cloud characterized by horizontal layering with a uniform base, as opposed to convective or cumuliform clouds that are formed by rising thermals.
High Clouds
The high cloud group consists of Cirrus, Cirrostratus, and Cirrocumulus clouds. High clouds are made of ice crystals due to the cold air in the upper sky. The base of a high cloud above the surface can be anywhere from 6000-18000m in the tropics to 3000-8000m in the polar regions.
Middle Clouds
The term 'Middle Clouds' as it applies to the area of the weather can be defined as ' (or Mid-Level Clouds) - A term used to signify clouds with bases between 6,500 and 23,000 feet. At the higher altitudes, they may also have some ice crystals, but they are composed mainly of water droplets. Altocumulus, altostratus, and nimbostratus are the main types of middle clouds. This altitude applies to the temperate zone. In the polar regions, these clouds may be found at lower altitudes. In the tropics, the defining altitudes for cloud types are generally higher.
Low Clouds
There are 3 main types of lower level clouds: cumulus, stratocumulus and stratus. The bases of low clouds range from surface height to about 6500 feet. Stratus (St) Stratus is defined as low cloud that appears fragmented and thin. It can also occur in the form of a layer or sheet.
Clouds of Vertical Development
Clouds with vertical growth include cumulus and cumulonimbus clouds. These clouds grow high up into the atmosphere rather than spreading across the sky. They span all levels of the troposphere and can even rise up into the stratosphere. Clouds with vertical growth develop by warm air rising from the surface.
Fog
a thick cloud of tiny water droplets suspended in the atmosphere at or near the earth's surface that obscures or restricts visibility (to a greater extent than mist; strictly, reducing visibility to below 1 km).
Advection Fog
Advection fog occurs when a warm, moist, air mass flows across a colder surface. The air mass is cooled from below by the colder surface and, if the temperature of the air mass is reduced to the dew point, then fog forms.
Radiation Fog
Definition of radiation fog. : an evening fog over damp grounds or valleys resulting from cooling by radiation.
Upslope Fog
produced by the flow of moist air along upward sloping terrain.
Steam Fog
Sea smoke, frost smoke, or steam fog, is fog which is formed when very cold air moves over warmer water. Arctic sea smoke is sea smoke forming over small patches of open water in sea ice.
Frontal Fog (Precipitation Fog)
Frontal fog forms near a front when raindrops, falling from relatively warm air above a frontal surface, evaporate into cooler air close to the Earth's surface and cause it to become saturated.
Bergeron Process
The Wegener-Bergeron-Findeisen process (after Alfred Wegener, Tor Bergeron and W. Findeisen), (or "cold-rain process") is a process of ice crystal growth that occurs in mixed phase clouds (containing a mixture of supercooled water and ice) in regions where the ambient vapor pressure falls between the saturation vapor ...
Supercooled
Supercooling is the process of chilling a liquid below its freezing point, without it becoming solid. A liquid below its freezing point will crystallize in the presence of a seed crystal or nucleus around which a crystal structure can form.
Freezing Nuclei
Meteorology. Freezing nucleus, any particle that, when present in a mass of supercooled water, will induce growth of an ice crystal about itself; most ice crystals in the atmosphere are thought to form on freezing nuclei. See condensation nucleus.
Supersaturated
increase the concentration of (a solution) beyond saturation point.
Collision-Coalescence Process
Collision/Coalescence; The Bergeron Process. THE BERGERON PROCESS. In order for cloud droplets, which are very small, to become rain drops, they have to increase in size almost a million times.
Rain
moisture condensed from the atmosphere that falls visibly in separate drops.
Snow
atmospheric water vapor frozen into ice crystals and falling in light white flakes or lying on the ground as a white layer.
Sleet
a form of precipitation consisting of ice pellets, often mixed with rain or snow.
Glaze
thin shiny coating
Hail
pellets of frozen rain that fall in showers from cumulonimbus clouds.
Rime
frost formed on cold objects by the rapid freezing of water vapor in cloud or fog.
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