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On clear, calm nights, objects near the earth's surface cool rapidly by what?
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As surfaces such as twigs, leaves, and blades of grass cool below dew point temperature, water vapor begins to condense upon them, forming tiny visble specks of water called what?
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Weather Test 2; Sec2
| Question | Answer |
|---|---|
| On clear, calm nights, objects near the earth's surface cool rapidly by what? | emitting infrared radiation |
| As surfaces such as twigs, leaves, and blades of grass cool below dew point temperature, water vapor begins to condense upon them, forming tiny visble specks of water called what? | dew |
| if the air temperature should drop to freezing or below, the dew will freeze, becoming tiny beads of ice called what? | frozen dew |
| Because the coolest air is usually at ground level, dew is more likely to do what? | form on blades of grass than on objects several meters above the surface |
| Averaged for an entire year in middle latitudes, dew yields a blanket of water between what? | 12-50mm thick |
| Dew is more likely to form on what kinds of nights? why? | Nights that are clear and calm; clear nights allow objects near the ground to cool rapidly by emitting infrared radiation, and calm winds mean that the coldest air will be located at ground level |
| Cloudy, windy weather that inhibits rapid cooling near the ground and the forming of dew often signifies what? | The approach of a rain-producing storm system |
| Visible white frost forms on what kind of mornings at what dew point temperature? | on cold, clear, calm mornings when the dew point temperature is at or below freezing |
| what is it called when the air temperature cools to the dew point? | frost point |
| What happens when air temperature cools to the dew point and further cooling occurs? | water vapor can change directly to ice without becoming liquid first-deposition |
| What is it called when water vapor changes directly to ice without becoming liquid first | Deposition |
| What are the delicate, white crystals of ice that form in the manner of deposition? | frost (also hoarfrost and white frost) |
| What has a treelike branching pattern that easily distingusihes it from the nearly spherical beads of frozen dew? | frost |
| What do the terms freeze and black frost refer to? | In very dry weather when the air temperature may become quite cold and drop below freezing without ever reaching the frost point, and no visible frost forms |
| What happens to relative humidity and to the air when air cools to the dew point? | relative humidity becomes 100% and air is saturated |
| To produce cloud droplets, what must be present? | there must be airborne particles on which water vapor can condense? |
| tiny particles upon whose surfaces condensation of water vapor begins in the atmosphere | condensation nuclei |
| Condensation nuclei that are quite small and have a radius less than 0.2 um? | Aitken nuclei |
| What are particles ranging in size from 0.2 to 1 um | large nuclei |
| What are particles that are larger and have a radii exceeding 1um? | giant nuclei |
| what is the condensation nuclei most favorable for producing clouds? | cloud condensation nuclei |
| What is the condensation nuclei that has radii of 0.1 um or more? | cloud condensation nuclei |
| Usually 100-1000 nuclei of what size exist in a cubic centimeter of air? | cloud condensation nuclei |
| How do cloud condensation nuclei enter the atmosphere? | dust, valcanoes, factory smoke, forest fires, salt from ocean spray, and even sulfate particles emitted by phytoplankton in the oceans |
| What provides the major source of cloud condensation nuclei in the marine atmosphere? | sulfates |
| What happens because most particles are relased into the atmosphere near the ground? | the largest concentrations of nuclei are observed in the lower atmosphere the earth's surface |
| What happens because condensation nuclei are extremely light? | they can remain suspended in the air for days |
| Where are condensation nuclei most abundant? | over industrial cities, where highly poluted air may contain nearly 1 million particles per cubic centimeter? |
| "water-seeking" | hygroscopic |
| What are particles where water vapor condenses upon these surfaces when the relative humidity is considerably lower than 100% | hygroscopic |
| Why is it that in humid weather, it is difficult to pour salt from a shaker? | because water vapor condenses onto the salt crystals, sticking them together |
| "water-repelling" | hydrophoobic |
| What are particles such as oils, gasoline, and paraffin waxes that resists condensation even when the relative humidity is above 100% | hydrophobic |
| What is a layer of dust or salt particles suspended above the region? | haze |
| Why are distant objects usually more visible in the afternoon that in the morning? | During the warm afternoon the relative humidity of the air is often below the point where water vapor begins to condense, even on active hygroscopic nuclei |
| Tiny dry haze particles selectively scatter some rays of sunlight, while allowing others to penetrate the air. What does this scattering effect produce? | a bluish color when viewed against a dark background and a yellowish tint when viewed against a light colored background |
| what happens when relative humidity reaches about 75%? | condensation may begin on the most active hygroscopic nuclei, producing a wet haze |
| What happens when relative humidity increases from about 60% to 80%? | the scattering effect increases by a factor of nearly 3 |
| Not only does wet haze restrict visibility more than dry haze, it also appears what color? | dull gray or white |
| Near seashores and in clean air over the open ocean, large salt particles suspended in the air with a high relative humidity oftend produce what? | a thin white veil across the horizon |
| What continually happens when water vapor condesnses onto hygroscopic nuclei at relative humidities as low at 75%? | the process of condensation begins |
| What happens as the relative humidity gradually approaches 100%? | the haze particles grow larger, and condensation begins on the less-active nuclei |
| What happens when visibility of relative humidity lowers to less than 1 km, and when the air is wet with countless millions of tiny floating water droplets? | the wet haze becomes a cloud resting near the ground (fog) |
| What is a cloud resting near to the ground? | fog |
| Is fog over dirty cities or over the ocean thicker? | cities |
| The smaller number of condensation nuclei over the middle of the ocean produce (more/less), but (bigger/smaller) | less; bigger |
| City air with its abundant nuclei produces many tiny fog droplets which greatly increases the thickness of what? and reduces what? | fog; visibility |
| What is fog that pollutes air that can turn acidic as the tiny liquid droplets combine with gaseous impurities, such as oxides of sulfur and nitrogen? | Acid fog |
| What happens as tiny fog droplets grow larger? | They become heavier and tend to fall toward the earth |
| In what 2 ways does fog form? | by cooling (air is cooled below its saturation point); by evaporation and mixing (water vapor is added to the air by evaporation, and the moist air mixes with relatively dry air) |
| Once fog forms it is maintained by new fog droplets, which constantly form on what? | Available nuclei |
| How can the air cool so that a cloud will form near the surface? | Radiation and conduction are the primary means for cooling nighttime air near the ground |
| What is fog produced by the earth's radiaitonal cooling? | radiaiton fog |
| what is another name for radiation fog? | ground fog |
| When does radiaiton fog form best? | on clear nights when a shallow layer of moist air near the ground is overlain by drier air |
| HOW DOES A LIGHT BREEZE (of less than 5 knots) HELP PROMOTE THE FORMATION OF RADIATION FOG? | slight air movement brings more of the moist air in direct contact with the cold ground, and the transfer of heat occurs more repidly |
| How does a strong breeze tend to prevent radiation fog from forming? | By mixing the air near the surface with the drier air above |
| Why do we normally see radiation fog forming in low-lying areas? | because cold, heavy air drains downhill and collects in valley bottoms |
| Why is radiation fog frequently called valley fog? | heavy air drains downhill and collects in valley bottoms |
| What is another aspect that make river valleys susceptible to radiation fog? | the cold air and high moisture content in them |
| Radiation fogs form (downward/upward)from the ground as the night progresses and are usually the deepest around sunrise? | upward |
| When is an occasion where fog may form after sunrise? | when evaporation and mixing take place near the surface; this usually occurs at the end of a clear, calm night as radiational cooling brings the air temperature close to the dew point in a rather shallow layer above the ground |
| Fog does not "burn off" but rather, the sun does what? | penetrates the fog and warms the ground, causing the air temperature in contact with the ground to increase |
| The warm air rises and mixes with the foggy air above increasing what? | the temperature of the foggy air |
| In the slightly warmer air, some of the fog droplets evaporate, allowing more sunlight to reach the ground, which produces what? | more heating, and soon the fog completely evaporates and disappears |
| In terms of fog, what do satellite images show? | that a blanket of radiation fog tends to evaporate (burn off) first around its periphery, where the fog is usually thinnest |
| What happens when fog is thick, with little sunlight penetrating it, and there is little mixing along the outside edges? | the fog may dissipate |
| What is it called when the fog no longer touches the ground, and a strong inversion exists above it? | high inversion fog |
| What is the low cloud above the ground? | status, or high fog |
| How is cooling surface air to its saturation point accomplished? | by warm moist air moving over a cold surface |
| What occurs when warm, moist air moves over a cold surface and the air cools to below its dew point | advection fog |
| What is a good example of advection fog? | the Pacific Coast during the summer |
| What is the main reason fog forms over the Pacific coast during the summer? | the surface water near the coast is much colder than the surface water farther offshore; warm moist air from pacific is carried by winds over cold coastal water; air temp drops and fog is produced |
| How is advection fog different than radiation fog? | it always involves the movement of air, so when there is a stiff summer breeze |
| As summer winds carry the fog inland over the warmer land, what happens? | The fog near the ground dissipates, leaving a sheet of low-lying gray clouds that block out the sun |
| Why is advection fogs important to the scenic beauty of the Pacific coast? | they provide moisture to the coastal redwoo trees |
| How does advection fog help redwood trees? | much of the fog moisture collected by the needles and branches of the redwoods drips to the ground (fog drip) where it is utilized by the tree's shallow root system |
| What fog prevails where two ocean currents with different temperatures flow next to one another? | Advection fog |
| Why does advection fog form over land? | In winter, warm moist air from the Gulf of Mexico moves northward over progressively colder an dslightly elevated lands; as the air coolts to its saturation point, a fog forms in the southern US |
| What causes advection-radiation fog? | because the cold ground is often the result of radiational cooling |
| What is fog that forms as relatively warm moist air moves over a colder surface that cooled mainly by radiational cooling? | advection-radiation fog |
| How is an ice fog produced? | in extremely cold arctic air when ice crystals form instead of water droplets |
| When does radiation fog tend to form? | on clear, relatively calm nights when cool, moist surface air is overlain by drier air and rapid radiational cooling occurs |
| When does advection fog form? | when the wind moves moist air over a cold surface and the moist air cools to its dew point |
| What is fog that forms as moist air flows up along an elevated plain, hill, or mountain? | upslope fog |
| When does upslope typically form? | during the winter and springon the eastern side of the rockies, where the eastward-sloping plains are nearly a kilometer higher than the land farther east |
| When does upslope fog form? | as moist air slowly rises, cools, and condenses over elevated terrain |
| What happens as cold air moves from the lower eastern plains westward? | the air gradually rises, expands, become cooler, and if sufficiently moist-a fog form |
| what is a fog form that lasts over an extensive area for many days? | upslope fogs |
| What is a fog that forms by the mixing of two unsaturated masses of air? | evaporation for |
| What is a common form of evaporation-mixing fog that forms when cold air moves over warm water? | steam fog |
| What kind of fog forms above a heated swimming pool in the winter? | steam fog |
| What is a column of condensed vapor that rises from a fog layer that whirs which appears similar to the dust devils on land | steam devils |
| Over the ocean in polar regions, steam fog is referred to as what? | arctic sea smoke |
| Steam fog may form above a wet surface on a sunny day, what is this fog commonly observed after? | after a rainshower as sunlight shines on a wet road, heats the asphalt, and quickly evaporates the water |
| What is another name for frontal fog? | precipitation fog |
| What is fog produced when sufficient water vapor is added to the air by evaporation, and the moist air mixes with relatively drier are. | frontal fog |
| In the US, where is fog dense more prevalent? | In coastal margins (especially those regions lapped by cold ocean curents |
| Where is the foggiest spot near sea level in US? | Cape Disappointment, Washington |
| Where is there 2556 hours of dense fog each year in the US? | mouth of Columbia River |
| the amount of time the air temperature during the winter must remain below a certain value so that fruit and nut trees will grow properly during the spring and summer? | Winter chilling |
| What are extra head lamps that are just above bumper that are directed downward into the clear space where they provide iimproved visiblity | fog lamps |
| Are fog reglated problems confined to land? | no, dense fog in the open sea hampers navigation |
| dew, frost, and frozen dew generally form on what kinds of nights? | clear nights when the temperature of objects on the surface cools below the air's dew-point temp |
| Visible white frost forms in saturated air when the air temperature is at or below what? | freezing |
| What is the process where water vapor can change directly to ice | deposition |
| a visible aggregate of tiny water droplets or ice crystals supspended in the air? | clouds |
| latin word for stratus? | layer |
| Latin name for cumulus | heap |
| latin word for cirrus | curl of hair |
| latin word for nimbus | violent rain |
| sheet like cloud | stratus |
| puffy cloud | cumulus |
| wispy cloud | cirrus |
| rain cloud | nimbus |
| 3 high clouds | Cirrus, cirrostratus, cirrocumulus |
| 2 middle clouds | altostratus, altocumulus |
| 3 low clouds | stratus, stratocumulus, nimbostratus |
| 2 clouds with vertical developmet | cumulus, cumulonimbus |
| cloud group above 6000 m (20,000 ft) | high clouds |
| cloud group where air is quite cold and dry, high clouds are composed almost exclusively of ice crystals and are also thin | high clouds |
| Cloud group where clouds appear white, except near sunrise and sunset, when the unscattered components of sunlight are reflected from underside of clouds | high clouds |
| clouds that are thing, wispy clouds blown by high winds into long streamers (mares' tails) | cirrus |
| clouds that look like a white, feathery patch with a faint wisp of a tail at one end | cirrus |
| clouds that usually move across the sky from west to eat, indicating the prevailing winds at their elevation, and generally point to fair, pleasant weather | cirrus |
| clouds that are seen less frequently than cirrus, appear as small, rounded, white puffs that may occur individually or in long rows | cirrocumulus |
| clouds that have a rippling appearance that resemble scales of fish ("mackerel sky") | cirrocumulus |
| cloud that seldom cover more than a small portion of the sky | cirrocumulus |
| thin sheetlike clouds that often cover the entire sky | cirrostratus |
| clouds that are thin that the sun and moon can be clearly seen through them | cirrostratus |
| clouds where ice crystals bend the light passing through them and will often produce a halo (ring of light that encircles the sun or moon) | cirrostratus |
| clouds that give sky a glary white appearance and fequently form ahead of an advancing storm-can be used to predict rain or snow within 12-24 hours | cirrostratus |
| cloud group based 2000-7000 m (6500 to 23,000 ft) | middle clouds |
| cloud group that is composed of water droplets and -when temperatures become low enough-some ice crystals | middle clouds |
| clouds that are composed mostly of water droplets and are rarely more than 1 km thick | altocumulous |
| cloud that appears as gray, puffy masses, sometimes rolled out in parallel waves or bands | altocumulus |
| cloud where one part is darker than another, which helps to separate it from the higher cirrocumulus | altocumulus |
| cloud that looks like little castles (castellanus) in the sky indicating the presence of rising air at cloud level | altocumulus |
| cloud where apprearance come on warm, humid summer morning often portends thunderstorms by late afternoon | altocumlus |
| cloud that is a gray or blue-gray cloud composed of ice crystals and water droplets | altostratus |
| what clouds cover the entire sky across an area that extends over many hundreds of square kilometers? | altostratus |
| In the thinner section of what clouds, the sun or moon may be dimly visible as a round disk, as if the sun were shinning through ground glass; what is this appearance referred to? | altostratus; watery sun |
| What clouds often form ahead of storms having widespread and relatively continuous precipitation | altostratus |
| with what cloud, if precipitation falls from an altostratus, its base usually lowers? | altostratus |
| what cloud is classified if precipitation reaches the ground? | nimbostratus |
| What cloud group has bases lying below 2000 m (65000 ft) | low clouds |
| what cloud group almost always composed of water droplets; but in cold weather contain ice particles and snow | low clouds |
| clouds that are dark gray wet-looking cloudy layer associated with more or less continuously falling rain or now | nimbostratus |
| How intense is the precipitation in the nimbostratus? | usually light or moderate-never heavy |
| What is the base of the nimbostratus cloud like? | is normally impossible to identify clearly and its top may be over 3 km higher |
| since lower clouds drift rapidly with the wind, they form irregular shreds with a ragged appearance called what? | stratus fractus, or scud |
| What clouds are low lumpy clouds that appear in rows, in patches, or as rounded masses with blue sky visible between the individual cloud elements | stratocumulus |
| clouds that appear near sunset as the spreading reamins of a much larger cumulus cloud | stratocumulus |
| Occasianlly, the sun will shine through the cloud breaks producing band of light that appear to reach the ground called what? | crepuscular rays |
| What cloud is a uniform grayish cloud that often covers the entire sky? | stratus |
| what cloud resembles a fog that does not reach the ground | stratus |
| Normally, no precipitation falls from these clouds, but sometimes it is accompanied by a light mist or drizzle | stratus |
| what cloud commonly occurs over Pacific and Atlantic coastal water in summer | Stratus |
| what cloud takes on a variety of shapes, but most often it looks like a piece of floating cotton with sharp outline and a flat base | cumulus |
| Scattered convective clouds with a flat base | cumulus |
| What cloud has lots of blue sky between the individual cloud elements | cumulus |
| What cloud burns off after sunset | cumulus |
| cumulus cloud associated with weather | cumulus humilis |
| ragged-edge cumulus clouds that are smaller than cumulus humilis and scattered across the sky | cumulus fractus |
| cloud resembes head of cauliflower | cumulus congestus, or towering cumulus |
| a thunderstorm cloud | cumulonimbus |
| cloud develops electrical charges-thunder and lightning | cumulonimbus |
| cloud may produce severe weather-tornadoes, hailstorms, lightning and thunder, heavy rainfall | cumulonimbus |
| cloud may tower into the stratosphere | cumulonimbus |
| clouds have flattened anvil-shaped tops | cumulonimbus |
| severe clouds often develop ahead of the cold fronts, bringing severe weather | cumulonimbus |
Created by:
arcall