Chapter 8

Question 1

Mid-latitude cyclone

Answer 1

Cyclonic storm that forms primarily in the middle latitudes. Its formation is triggered by the development of troughs in the polar jet stream. These storms also contain warm, cold and occluded fronts. Atmospheric pressure in their center can get as low as 970 millibars. Also called wave cyclones or frontal cyclones.

Question 2

cold front

Answer 2

A transition zone in the atmosphere where an advancing cold air mass displaces a warm air mass. Normally associated with mid-latitude cyclones

Question 3

warm front

Answer 3

A transition zone in the atmosphere where an advancing warm air mass displaces a cold air mass. Associated with mid-latitude cyclones.

Question 4

tropical cyclones

Answer 4

Another name commonly used to describe a hurricane.

Question 5

hurricanes

Answer 5

An intense cyclonic storm consisting of an organized mass of thunderstorms that develops over the warm oceans of the tropics. To be classified as a hurricane, wind speeds in the storm must be greater than 118 kilometers per hour (73 miles per hour)

Question 6

thunderstorms

Answer 6

A storm that typically ranges in size from several kilometers (several miles) to over 50 kilometers (30 miles) in diameter created by the rapid lifting of moist warm air which creates a cumulonimbus cloud. Thunderstorms can occur in isolation as a single celled storm or as a multi-celled storm arranged in a cluster or as a line of adjacent cells (called a squall line) found along or in front of a mid-latitude cyclone cold front. Thunderstorms can have the following severe weather associated with them: strong winds; hail; lightning; tornadoes; thunder; and heavy rain

Question 7

adiabatic expansion

Answer 7

In our planet’s atmosphere, adiabatic expansion occurs when a parcel of air rises in elevation. The decrease in atmospheric pressure with higher elevation causes the parcel to increase in size and the gas molecules in the parcel to move further apart from each other, which in turn causes the temperature in the parcel to decrease at a rate of 0.98°C per 100 meters (0.54°F per 100 feet) if saturation has not occurred

Question 8

cumulus

Answer 8

Puffy clouds with relatively flat bases. Cumulus clouds form when moist warm air bubbles vertically escape from the Earth’s surface. Found in an altitude range between 300 to 2,000 meters (984 to 6,560 feet)

Question 9

maritime tropical air masses

Answer 9

Air mass that forms over extensive ocean areas of the low latitudes. Around North America, these system form over the Gulf of Mexico and the eastern tropical Pacific. Maritime Tropical air masses are warm and humid in both winter and summer. In the Northern Hemisphere, maritime tropical air masses can normally stable during the whole year if they have form just west of a continent. If they form just east of a continent, these air masses will be unstable in both winter and summer.

Question 10

updrafts

Answer 10

Upward movement of air in the atmosphere. Compare with downdraft.

Question 11

orographic uplift

Answer 11

The forced uplift of an air mass because of the presence of a topographic obstruction. This uplift also causes the cooling of the air mass. If enough cooling occurs condensation can occur and form into orographic precipitation. Also called orographic lifting

Question 12

convectional lifting

Answer 12

The vertical lifting of air parcels through convective heating of the atmosphere. This process can initiate adiabatic processes inside the air parcel.

Question 13

air mass thunderstorm

Answer 13

An ordinary single-celled thunderstorm that develops from a mass of unstable air. Compare with severe thunderstorm

Question 14

downdrafts

Answer 14

Downward movement of air in the atmosphere. Compare with updraft.

Question 15

coalescence

Answer 15

Process where two or more falling rain drops join into a single larger drop because of a midair collision

Question 16

cold front

Answer 16

A transition zone in the atmosphere where an advancing cold air mass displaces a warm air mass. Normally associated with mid-latitude cyclones.

Question 17

dry line

Answer 17

A boundary that separates dry and moist air in the warm sector of a mid-latitude cyclone wave. Found ahead of the cold front

Question 18

gust front

Answer 18

A boundary layer in the lower atmosphere found ahead of a thunderstorm that separates cold storm downdrafts from warm humid surface air. Winds in this phenomenon are strong and fast

Question 19

temperature inversion

Answer 19

Situation where a layer of warmer air exists above the Earth’s surface in a normal atmosphere where air temperature decreases with altitude. In the warmer layer of air, temperature increases with altitude

Question 20

mesocyclone

Answer 20

A cylinder of cyclonically flowing air that form vertically inside a severe thunderstorm. They measure about 3 to 10 kilometers (1.9 to 6.2 miles) across. About 50% of these weather events spawn tornadoes.

Question 21

tornado

Answer 21

A vortex of rapidly moving air associated with some severe thunderstorms. Winds within the tornado funnel may exceed 500 kilometers per hour (310 miles per hour).

Question 22

waterspouts

Answer 22

A vortex of rapidly moving air over water that is associated with some thunderstorms.

Question 23

Tornado Alley

Answer 23

A popular term used to describe a region in North America that receives an extraordinary high number of tornadoes. This term has not been specifically defined by mainstream meteorology or climatology science. One definition of this term suggests the region extends from north-central Texas northwards to South Dakota and southern edge of Minnesota

Question 24

Air mass

Answer 24

A large body of air whose temperature and humidity characteristics remain relatively constant over a horizontal distance of hundreds to thousands of kilometers (miles). Air masses develop their climatic characteristics by remaining stationary over a source region for a number of days. Air masses are classified according to their temperature and humidity characteristics

Question 25

Maritime polar

Answer 25

Air mass that forms over extensive ocean areas of the middle to high latitudes. Around North America, these air mass system form over the Atlantic and Pacific oceans at the middle latitudes. Maritime Polar air masses are mild and humid in summer and cool and humid in winter. In the Northern Hemisphere, maritime polar air masses are normally unstable during the winter. In the summer, atmospheric stability depends on the position of the air mass relative to a continent. Around North America, Maritime Polar air masses found over the Atlantic are stable in summer, while Pacific systems tend to be unstable.

Question 26

continental polar

Answer 26

Air mass that forms over extensive landmass areas of middle to high latitudes. In North America, these systems form over northern Canada. Continental Polar air masses are cold and very dry in the winter and cool and dry in the summer. These air masses are also atmospherically stable in all seasons.

Question 27

Maritime tropical

Answer 27

Air mass that forms over extensive ocean areas of the low latitudes. Around North America, these system form over the Gulf of Mexico and the eastern tropical Pacific. Maritime Tropical air masses are warm and humid in both winter and summer. In the Northern Hemisphere, maritime tropical air masses can normally stable during the whole year if they have form just west of a continent. If they form just east of a continent, these air masses will be unstable in both winter and summer.

Question 28

Continental tropical

Answer 28

Air mass that forms over extensive landmasses areas of the low latitudes. In North America, these systems form over southwestern United States and northern Mexico. Continental Tropical air masses are warm and dry in the winter and hot and dry in the summer. These air masses are also generally unstable in the winter but stable in the summer

Question 29

continental arctic

Answer 29

Air mass that forms over extensive landmass areas of the high latitudes. In the Northern Hemisphere, these systems form only in winter over Greenland, northern Canada, northern Siberia, and the Arctic Basin. Continental Arctic air masses are very cold and extremely dry. These air masses are very stable.

Question 30

frontal lifting

Answer 30

Lifting of a warmer or less dense air mass by a colder or more dense air mass at a frontal transitional zone. This process causes the water vapor in the warmer air to cool and then condense or freeze forming clouds and precipitation.

Question 31

stationary fronts

Answer 31

A transition zone in the atmosphere where there is little movement of opposing air masses and winds blow towards the front from opposite directions.

Question 32

cold front

Answer 32

A transition zone in the atmosphere where an advancing cold air mass displaces a warm air mass. Normally associated with mid-latitude cyclones.

Question 33

warm front

Answer 33

A transition zone in the atmosphere where an advancing warm air mass displaces a cold air mass. Associated with mid-latitude cyclones

Question 34

occluded fronts

Answer 34

A transition zone in the atmosphere where an advancing cold air mass sandwiches a warm air mass between another cold air mass pushing the warm air into the upper atmosphere. Associated with mid-latitude cyclones

Question 35

mid latitude cyclone

Answer 35

Cyclonic storm that forms primarily in the middle latitudes. Its formation is triggered by the development of troughs in the polar jet stream. These storms also contain warm, cold and occluded fronts. Atmospheric pressure in their center can get as low as 970 millibars. Also called wave cyclones or frontal cyclones.

Question 36

frontal cyclones

Answer 36

Another name for mid-latitude cyclone.

Question 37

nimbostratus clouds

Answer 37

Dark, gray low altitude cloud that produces continuous precipitation in the form of rain or snow. Found in an altitude range from the surface to 3,000 meters (9,840 feet).

Question 38

altostratus

Answer 38

Gray-looking middle altitude cloud that is composed of water droplets and ice crystals. Appears in the atmosphere as dense sheet like layer. Can be recognized from stratus clouds by the fact that you can see the Sun through it. Found in an altitude range from 2,000 to 8,000 meters (6,500 to 26,250 feet).

Question 39

cirrostratus

Answer 39

High altitude sheet like clouds composed of ice crystals. These thin clouds often cover an extensive area of the sky. Found in an altitude range from 5,000 to 18,000 meters (16,400 to 59,050 feet)

Question 40

cyclogenesis

Answer 40

The process of cyclone formation, maturation, and death. Associated with tropical storms, hurricanes, and mid-latitude cyclones

Question 41

Intertropical Convergence Zone

Answer 41

Zone of low atmospheric pressure and ascending air located at or near the equator. Rising air currents are due to global wind convergence and convection from thermal heating. Location of the thermal equator.

Question 42

Subtropical High Pressure Zone

Answer 42

Surface zone of atmospheric high pressure located at about 30° North and South latitude. These high pressure systems produced by vertically descending air currents from the Hadley Cell.

Question 43

easterly waves

Answer 43

An atmospheric trough in the tropical trade winds. Occasionally these systems intensify into tropical storms and hurricanes

Question 44

Hurricane

Answer 44

An intense cyclonic storm consisting of an organized mass of thunderstorms that develops over the warm oceans of the tropics. To be classified as a hurricane, wind speeds in the storm must be greater than 118 kilometers per hour (73 miles per hour).

Question 45

Tropical depression

Answer 45

An organized group of thunderstorms often found over a tropical ocean that generates a cyclonic flow of between 37 and 63 kilometers per hour (23 to 38 miles per hour). Can develop into a hurricane.

Question 46

Tropical storms

Answer 46

An organized group of thunderstorms often found over a tropical ocean that generates a cyclonic flow of between 64 and 118 kilometers per hour (39 to 73 miles per hour). Often develops into a hurricane

Question 47

Saffir-Simpson Scale

Answer 47

Tropical storm and hurricane intensity classification system developed in 1971 by civil engineer Herbert Saffir and meteorologist Bob Simpson. This system has seven levels. The first two categories describe two stages of storm development before becoming a hurricane: TD – tropical depression and TS – tropical storm. Hurricanes are categorized according to levels of intensity that range from 1 to 5. A major hurricane is considered to be categorized 3 and above. These levels are based on the speed of the storm’s sustained winds and its lowest surface atmospheric air pressure.

Question 48

Storm surge

Answer 48

Relatively rapid rise in the height of the ocean along a coastline. Often caused by the winds associated with a tropical storm or hurricane pushing water towards land.