ESC1000 Chapter 17 Moisture, Clouds and Precipitation
|Melting||Substance solid transforms to liquid. A cooling process.|
|Freezing||liquid transforms to solid. A heating process.|
|Evaporation||liquid transforms to vapor. A cooling process|
|Condensation||Vapor transforms to liquid. A heating process.|
|Sublimation||A solid transforms to a gas, skipping the liquid phase. A cooling process.|
|Deposition||A gas transforms to a solid. A heating process.|
|Humidity||the amount of water vapor in air.|
|Higher||When temperature is higher, the amount of water vapor air can hold is _______|
|Lower||When temperature is lower, the amount of water vapor air can hold is _______.|
|Unsaturated||When a given parcel of air is holding less water than it can actually hold it is___________.|
|Saturated||When a given parcel of air is holding all the water vapor it can hold, it is _________.|
|Mixing ratio||specific humidity|
|Specific humidity||Ratio of the amount of water vapour in air by weight, compared to the mass of air it is in. Not affected by temperature.|
|Absolute humidity||Ratio of the amount of water vapour in air by volume, compared to the volume of air it is in. Not affected by temperature.|
|Relative humidity||Ratio of the amount of water vapour in air compared to the amount needed to saturate the air at the same temperature. Given as a percentage. Is strongly affected by temperature.|
|Relative humidity||how much water the air is holding relative to the amount is can potentially hold, its capacity. Is strongly affected by temperature.|
|Increases||What happens to relative humidity when temperature increases?|
|Decreases||What happens to the capacity of air to hold water vapour when temperature decreases?|
|Increases||What happens to relative humidity when the water vapour content of the air stays the same, but the temperature drops?|
|Dew point||The temperature that a parcel of unsaturated air would have to fall to, in order to become saturated. Given as a temperature.|
|Hygrometer||A device to measure humidity|
|Sling psychrometer||a type of hygrometer.|
|Adiabatic temperature change||When a gas changes temperature because of a pressure change (either expansion or compression).|
|Orographic lifting||When air is forced up and over mountains|
|Frontal wedging||weather process where a body of cold air meets hot air, and the hot air is forced up and over the cold air, it expands, cools, condensation occurs and clouds form.|
|Convective lifting||weather process where the sun heats the land surface, which heats the adjacent air, and then the heated air rises.|
|Thermal||another name for convective lifting.|
|Convergence||weather process where wind (with air of similar temperatures) from two directions meet and the only way for the air to go is up.|
Cloud that is high level and wispy or light and patchy in form, made of ice crystals and is always up high.
Form of cloud that is puff balls, often with a flat base (but can lose flat base due to air circulation).
Form of cloud in sheets or layers, that may cover the whole sky, and doesn't have separate clouds.
Form of cloud that is high in level and puff ball in form.
high level, very light layers of cloud.
|Alto||general term for clouds that are at mid level|
mid-level puffball clouds.
clouds that are mid-level, and bigger and denser than cirrocumulus.
clouds at mid-level that form a light sheet that lets the sun or moon show as a bright spot.
|stratus||general term for clouds that are low level; often cover much of the sky|
clouds that are low-level layers of cumulus clouds, that begin to touch each other and fuse.
clouds that are low-level, uniform layer, usually very dark, that bring strong precipitation.
|Nimbus||general term for clouds that means rainy in Latin.|
Clouds that are the product of growth of cumulus which can form huge thunderheads.
|Fog||a cloud that forms at or near the ground.|
|Mist||precipitation that reaches the surface in liquid drops of the smallest size. 0.005-0.05mm diameter.|
|Drizzle||precipitation that reaches the surface in liquid form, drops 0.05-0.5mm diameter.|
|Rain||precipitation that reaches the surface in liquid form, drops 0.5-5mm diameter.|
|Snow||precipitation that reaches the surface in form of ice crystals or aggregates of crystals|
|Sleet||precipitation that reaches the surface in form of small ice particles. Often falls as rain but then passes through a cold layer that freezes the drops.|
|Hail||precipitation that reaches the surface in form of larger pieces of ice. Formed in cumulonimbus clouds in updrafts of up to 100mph.|
|Glaze||forms when rain freezes as it hits a freezing surface, forming a thin coating of ice. Eg black ice.|
|Rime||deposit of ice crystals that forms directly on cold surfaces from fog.|
|Graupel||Soft hail, which forms when rime coats snowflakes on their way down.|
|Bergeron Process||formation of precipitation, where water condenses, and freezes, then falls frozen or melted as rain.|
|Collision-coalescence process||formation of precipitation, where tiny droplets accumulate, fall, and collide with other small droplets until rain drops form and fall.|
|Atmospheric Stability||Air parcel resists upward displacement (i.e. air parcel is colder than surrounding environment or denser, when it tends to sink back to original level)|
Flickr Creative Commons Images
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- "Cirrus" image
- "Cumulus" image
- "Stratus" image
- "Cirrocumulus" image
- "Cirrostratus" image
- "Altocumulus" image
- "Altocumulus" image
- "Altostratus" image
- "stratocumulus" image
- "Nimbostratus" image
- "Cumulonimbus" image
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