the state of the atmosphere at a certain time and place

the year round weather typical of a certain place

the study of weather and of the atmospheric conditions that produce weather

scientists who study meteorology

any solid or liquid water that falls to the earth including rain, sleet, hail, and snow

process of going from a solid to a liquid is called

process of going from a liquid to a solid

the process of a liquid becoming a gas

the product of a gas becoming a liquid

A condition in which the air is continually supplied with water vapor until it eventually is unable to hold any more water.  At this point the water in the air is evaporating at the same rate that it is condensing and the air is ___________

the amount of water vapor in air

A term for the amount of actual humidity relative to the humidity of saturated air under the same conditions; this ratio is usually given as a percent

The temperature at which air that is cooling becomes saturated (which depends on the actual amount of water in the air) and reaches the temperature at which the water in the air turns into liquid and condenses on surfaces

when the ground cools below the dew point of the surrounding air the water vapor in the air that touches the cooler ground condenses into these drops of water

when air above the earth's surface cools below its dew point the air's water vapor >condenses< around microscopic particles such as dust, soot, smoke, and sea salt, that are floating in the atmosphere. These particles are called this because each serves as the >nucleus< or center that the water vapor condenses onto

if the dew point of air is below the freezing point of water, it is usually called this

when the temperature of air drops below the frost point, the air's water vapor can skip the liquid stage by changing directly into a crystal of ice on a surface; this is this process

light, feathery deposits of ice crystals

water vapor in air that drops below the frost point will remain supercooled until it can crystallize onto microscopic particles known as this (or ice nuclei) they become the center for ice crystals

water vapor may become this when its temperature is below freezing point

when the temperature falls below the dew point, the air's water vapor condenses into tiny droplets of liquid water ; if the dew point is below freezing tiny ice crystals form instead. If these droplets or ice crystals are present in large enough numbers that they are visible as a whole, they are called a ______

most clouds result from ____________ ___________ of moist air

meteorologists classify clouds into ten basic categories based on ______ __ ______

a heap, clouds that are white, billowy clouds that resemble piles of cotton puffs with flat basis

if strong enough updrafts are present, a cumulus cloud may grow into a huge, towering cloud that produces heavy rains, strong winds, lightning, thunder, and sometimes hail or tornadoes; these clouds are also known as thunderstorm clouds

to extend, to stretch, clouds that often form a flat, gray, layer of heavy clouds not far above the ground, appearing as a featureless, gray sheet, that covers the whole sky

extended heaps, the most frequent clouds, which form a low, heavy, layer of puffy gray clouds

extended cloud, although their bases can form at an altitude of up to 13,000 feet these clouds are sometimes classified as low-level clouds because they can also form below 6500 feet

high heap, clouds that look like cumulus or stratocumulus clouds but appear smaller from the ground and have their bases at higher altitudes

high and extended, clouds that are flat, sheetlike clouds that look similar to stratus clouds except that they are a lighter color

curl of hair, most common type of high-level cloud which are completely made of ice crystals

heaps of curls, clouds that are the least common type of high-level cloud they look like tiny puffs of cotton in the upper troposphere

extended curls, clouds that are thin, transculent and spread like a sheet similar to altostratus clouds

lens shaped, one interesting type of cloud is this almond-shape cloud

short for condensation, trails, in the upper troposphere where temperatures are often cold airplanes often produce their own artificial clouds known as this

when water vapor condenses in the layer of air near the ground it creates this basically stratus cloud that has developed at the surface of the earth

the cloud is this if the visibility is greater than one kilometer

the most common type of fog during long autumn nights when the ground grows cooler but the air is still moist

fog can also form when a warm, humid, breeze blows over a cold surface such as a cold lake the breeze cools until its temperature drops below the dew point forming a fog over the surface called this

often found along the slopes of mountains and can cover a large area for several days

often fog forms this way over lakes or rivers during the fall when the water is still warm but the surrounding air is cool

the mixture of smoke and fog

although the term smog originally described London's smoke-filled fogs, now the term usually refers to a different air problem that has nothing to do with fog. This smog is a thick, brownish haze that results from complex molecules released into the air by cars, buses, trucks, lawn mowers, some factories, and even certain trees and other plants

the movement of water from the earth's surface into the air and back to the surface

the most common precipitation, these are drops of liquid water falling from the clouds to the earth

drops of water larger than .5 millimeters in diameter

newly formed ice crystals begin to grow as they absorb water vapor from the cloud and as they stick to each other, eventually, the ice crystals will grow large enough to be this

as long as air temperatures below the cloud remain above freezing the raindrops will remain a liquid and fall to the earth as rain. this is this process which helps meteorologists understand why snow can fall on a mountain slope while rain falls in an adjacent valley

in clouds with temperatures above freezing such as in the Tropics, rain seems to form by this process. Larger than normal condensation nuclei cause the formation of giant cloud droplets. As these droplets drift downward they collide with smaller droplets and stick to them growing bigger in the process eventually the growing droplets become too big to remain suspended in the air and they begin to fall

meteorologists classify any liquid precipitation less than .5 millimeters in diameter as this

when the supercooled raindrops touch a freezing surface they turn to ice this is this phenomenon

because of the depth of the layer the raindrops have time to freeze and form tiny balls of ice or this before they hit the ground

in the united states this is basically ice pellets falling to the ground

perhaps the most beautiful form of precipitation which is made of snowflakes that fall to the ground

a sector plate that develops feathery branches on its arms forming a leaf or star-shaped pattern. most familiar snowflake shape

if the temperatures are well below freezing the snowflakes will be small and powdery this type of snow is light and does not stick to surfaces

warmer temperatures make the snowflakes stick to each other to form larger snowflakes on the ground these snowflakes form a heavy snow that sticks to surfaces this type of snow is this

according to the U.S. National Weather Service a snowfall with a visibility of over 1/2 mile is this

snow with visibility between 1/4 mile and 1/2 mile

snow with visibility of less than 1/4 mile

brief periods of light snowfall that result in little or no accumulation

a brief but intense snowfall

accumulates 4 inches or more in 12 hours or less or accumulates 6 inches or more in 24 hours or less

occurs when heavy snow and winds of at least 35 mph prevail for 3 or more hours

during a blizzard the large amounts of falling and blowing snow can reduce visibility to almost zero which is called this

consists of layered balls of ice that form in strong thunderstorms which occur most often in the spring and summer

the layered ball of ice now called this may fall to the ground

when an area receives abnormally low precipitation over a relatively long period causing a water shortage that affects people, crops, and the environment

defined by comparing an area's current precipitation with the area's typical precipitation and by analyzing how long the dry period lasts

usually occurs when precipitation cannot supply enough moisture to the ground to support an area's crops

occurs when a meteorological drought affects an area' ground water, streams, lakes, and reservoirs

this form of drought is based not on the physical water shortage but on the water shortage's effect on the people

a large body of air with relatively uniform temperature, humidity, and pressure

three factors that affect the density of an air mass

an air mass that forms over the Tropics that will be quite warm

an air mass that forms over a cold region

an air mass that forms over the sea and is generally very humid

an air mass that forms over land and is generally very dry

dry and cold air masses

dry and very cold air masses

sometimes an air mass remains stationary over a region for a long time if this occurs the region experiences this which is mostly the same general weather conditions will prevail from one day to the next

the boundary between a warm and cold air mass

when a warm air mass moves into a region occupied by a cold air mass the lighter warm air flows up and over the heavy cold air. because in this front the warm air is advancing it is called this

sometimes two air masses push against each other but neither advances in this case this type of front occurs

the combination of three air masses forms a Y-shaped front called this

a low that forms along a front is this