Advertisement Upgrade to remove ads

Latent heat

the heat energy absorbed or released by a substance during a phase change; example: when liquid water evaporates, the water absorbs energy from the environment, which becomes potential energy between the molecules; when wter vapor changes back into a liquid through the process of condensation, the energy is released to the surrounding air

Humidity

the amount of water vapor in the air; when water evaporates, the humidity of the air is increasing; as the temperature of the air increases, the air's ability to hold water vapor also increases; recall, warm air holds more water vapor than cool air

Absolute Humidity

the mass of water vapor contained in a given volume of air; a measure of the actual amount of water vapor in the air; however, as air moves, its volume changes as a result of temperature and pressure changes

Relative Humidity

a ratio of the actual water vapor content of the air to the amount of water vapor needed to reach saturation; a more common way to measure humidity; calculated by using the following formula: relative humidity (RH) %= actual water vapor content (g/kg)/saturation water vapor content (g/kg) *100

Relative Humidity is affected by

amount of water vapor-- at constant temperature and pressure, the more water vapor there is in the air, the higher the relative humidity; and temperature-- at constant water vapor content in the air, increased temperature leads to lower relative humidity adn decreased temperature leads to higher

psychrometer

an instrument used to measure relative humidity made of two thermometers; dry-bulb and wet-bulb (covered iwth a damp cloth); the difference between the readings indicates the amount of water vapor in the air; the larger the difference, the less water vapor in the air, therefore lower humidity; the smaller the difference, the more water vapor in the air, therefore higher humidity

dew point

the temperature a gas condenses into a liquid

Condensation

the process by which a gas, such as water vapor, becomes a liquid; before this can occur, the air must be saturated RH of 100%; air can become saturated: when water vapor is added through evaporation and when air cools to the dew point, which is the temperature a gas condenses into a liquid

Cloud

a collection of small water droplets or ice crystals in teh air; form as warm air rises and cools, condenses onto tiny particles of gas and dust in the atmosphere; classified based on shape and altitude; for water vapor to condense and forma cloud, a solid surface on which condensatino can take place must be available; the troposphere containts millions of particles of ice, salt, dust, smoke, and other particles serving as solid surfaces

Condensation nuclei

these suspended particles providing a surface necessary for water vapor to condense

Stratus Clouds

clouds are clouds forming in layers and have a flat, uniform base beginning to form at low altitudes; cover large areas of the sky and often block out the sun; form where a lyer of warm, moist air lies above a layer of cool air; overlying warm air cools to the dew point, creating a cloud

Nimbo/nimbus

means rain; nimbostratus clouds are dark stratus clouds usually producing heavy, continuous rainfall

Cumulus clouds

puffy, white clouds tending to have flat bottoms; form when warm, moist air rises and cools; normally indicate fair weather; if they get larger, they can produce thunderstorms-- cumulonimbus clouds

Cirrus clouds

thin, feathery clouds found at high altitudes; made of ice crystals due to low temperatures at higher altitudes in the troposphere; form as a result of strong winds; if they get thicker, cirrus clouds indicate a change in weather is coming

Cirro-

used to describe clouds forming at higher altitudes; normally made of ice crystals

Alto-

used to describe clouds forming at middle altitudes; can be made of both water droplets and ice crystals

Fog

water vapor that has condensed very near the surface of the Earth because air close to the ground has cooled

Radiation fog

a type of fog formed from teh nightly cooling of Earth; layer of air in contact with the ground becomes chilled to below the dew point

Advection fog

forms when warm, moist air moves across a cold surface; common along coasts

Precipitation

when water from the air (condensed clouds) returns to the Earth's surface

Rain

most common; begins as a drop smaller than a period at the end of a sentence

Snow

forms when temperatures are so cold, water vapor changes directly to solid and falls to the ground as a single crystal or snowflake

Sleet

forms when rain falls through a layer of freezing air; the rain freezes in the air, producing falling ice

Freezing rain

occurs when cold water droplets freeze when they make contact with Earth's surface

Hail

balls or lumps of ice falling directly from clouds; forms in cumulonimbus clouds; common during thunderstorms and tornadoes

Please allow access to your computer’s microphone to use Voice Recording.

Having trouble? Click here for help.

We can’t access your microphone!

Click the icon above to update your browser permissions above and try again

Example:

Reload the page to try again!

Reload

Press Cmd-0 to reset your zoom

Press Ctrl-0 to reset your zoom

It looks like your browser might be zoomed in or out. Your browser needs to be zoomed to a normal size to record audio.

Please upgrade Flash or install Chrome
to use Voice Recording.

For more help, see our troubleshooting page.

Your microphone is muted

For help fixing this issue, see this FAQ.

Star this term

You can study starred terms together

NEW! Voice Recording

Create Set