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Weather Vocabulary
7th Grade Weather Unit Study Guide
Term | Definition |
---|---|
air mass | a body of air with horizontally uniform temperature, humidity, and pressure |
air pressure | the force exerted by air, whether compressed or unconfined, on any surface in contact with it |
atmosphere | the envelope of gases surrounding the earth or another planet |
cirrus | wispy clouds made of ice crystals |
cold front | Fronts that form when/where cold air moves under warm air |
condensation | the process in which vapor changes into a liquid |
conduction | the process by which heat or electricity is directly transmitted through a substance when there is a difference of temperature or of electrical potential between adjoining regions, without movement of the material |
convection | the movement caused within a fluid by the tendency of hotter and therefore less dense material to rise, and colder, denser material to sink under the influence of gravity, which consequently results in transfer of heat |
Coriolis Effect | an effect whereby a mass moving in a rotating system experiences a force acting perpendicular to the direction of motion and to the axis of rotation. |
cumulus | a cloud forming rounded masses heaped on each other above a flat base at fairly low altitude. |
dew point | the atmospheric temperature (varying according to pressure and humidity) below which water droplets begin to condense and dew can form. |
Doldrums | an equatorial region of the Atlantic Ocean with calms, sudden storms, and light unpredictable winds. |
evaporation | the process of turning from liquid into vapor: |
exosphere | the outermost region of Earth's atmosphere; top half of thermosphere |
front | a boundary that forms between air masses |
global wind | wind systems that are a product of the Coriolis Effect; occurring globally at or near Earth's surface |
greenhouse effect | the trapping of the sun's warmth in a planet's lower atmosphere due to the greater transparency of the atmosphere to visible radiation from the sun than to infrared radiation emitted from the planet's surface. |
heat | the energy that is transferred between objects that are at different temperatures |
high pressure system | an area of high air pressure where air slowly sinks down, spreading toward areas of low pressure |
horse latitudes | a belt of calm air and sea occurring in both the northern and southern hemispheres between the trade winds and the westerlies. |
humidity | the amount of water vapor in the air |
ionosphere | the layer of the earth's atmosphere that contains a high concentration of ions and free electrons and is able to reflect radio waves.; lower layer of the thermosphere |
jet stream | narrow belts of high speed winds that blow from west to east |
land breeze | a breeze that blows toward the water from a piece of land; cooler air on land runs off the land toward the warm air on the water |
local wind | the movement of air over short distances |
low pressure system | an area of low air pressure where air rises; as it rises the air cools |
mesosphere | the layer of the atmosphere just above the stratosphere and below the thermosphere; located higher than planes can fly; destroys meteors before they hit the lithosphere |
mountain breeze | when the air along the mountain slopes cools and sinks into the valley |
occluded front | a warm and cold front mixed together |
ozone layer | a layer of ozone that is located in the middle of the stratosphere that protects us from harmful radiation |
polar easterlies | global winds that blow between 60 degrees and the poles; curve slightly west, produce snow and freezing weather |
precipitation | any form of water that falls to earth's surface from the clouds |
radiation | the transfer of energy in the form of electromagnetic waves |
relative humidity | the amount of water vapor in the air compared to the amount of water vapor it takes to reach saturation |
runoff | the draining away of water (or substances carried in it) from the surface of an area of land, a building or structure, etc. |
sea breeze | a cool breeze coming off of a body of water; cooler air runs off water towards the warmer land |
stationary front | Fronts that form when cold and warm air stops moving; causes many days of unchanging weather |
stratosphere | the layer of the atmosphere above the troposphere and below the mesosphere; planes fly there; contains ozone layer |
stratus | spread out clouds formed in flat layers; low stratus can cause rain and block out the sun |
temperature | a measure of the average amount of kinetic energy of particles |
thermal energy | the total amount of kinetic energy in particles |
thermal expansion | the increase in volume that occurs because of an increase in temperature |
thermosphere | the uppermost layer of the atmosphere; contains ionosphere and exosphere |
trade winds | global winds that blow between 30 degrees and the equator; curve slightly west |
troposphere | the lowest layer of the atmosphere where all weather occurs |
valley breeze | when the air in a valley flows up to the mountain slopes because there is higher pressure in the valley |
warm front | Fronts that form when/where warm air moves over cold air |
weather | the condition of the earth's atmosphere at a certain time and place |
westerlies | global winds that blow between 30 and 60 degrees; tend to curve east |
wind | the movement of air caused by differences in air pressure |