Unit 6

Question 1

What is the difference between weather and climate?

Answer 1

Weather is specific to place and time; climate is long-term patterns in temperature and precipitation

Question 2

What are the three properties of air, and what are they?

Answer 2

Temperature: average kinetic energy of the molecules in the air
Pressure: weight of the air above any particular point
Moisture: amount of water vapor in the air at any given time and place

Question 3

Temperatures vary seasonally around the world because of the way earth tilts on its axis and revolves around the sun.

Question 4

What affects the movement of air?

Answer 4

Air Pressure

Question 5

What are the two ways moisture is described, and what are they?

Answer 5

Relative humidity: The amount of water vapor in the air per unit of air, in %
Dew Point: The temperature at which the water vapor in the air condenses

Question 6

How are clouds formed?

Answer 6

Air holding water rises, cools, and moisture condenses to form clouds

Question 7

What are the 4 types of air masses, and where do they form?

Answer 7

Polar air mass: high latitudes near towards the earth’s poles
Tropical air mass: low latitudes
Continental air mass: over land
Maritime air mass: over water

Question 8

What is a thermograph?

Answer 8

A thermometer that automatically records its temperature readings onto a chart

Question 9

What are the two different types of barometers, and how do they measure air pressure?

Answer 9

Wet (liquid): Upside down tube is placed in a liquid reservoir; the air exerts pressure on the reservoir, causing the liquid to go up
Dry (aneroid): a small, circular, airtight hollow metal tubes containing air are linked to the needle; as air exerts pressure on the tubes, they shrink and cause changed in the needle

Question 10

What measures humidity?

Answer 10

A hygrometer

Question 11

How do hygrometers work?

Answer 11

Stands of horse or human hair (oils removed) attached to a lever-pen cause the lever-pen to move up or down over recording paper, showing the humidity

Question 12

What measures precipitation, and how do they work?

Answer 12

Rain gauge; It has a funnel that is 10 times larger than the area of the collecting bucket. The water collected in the rain gauge is measured in inches.
Radar: detects precipitation by sending out a pulsed radio signal (1 cm wavelength). If there is no precipitation, the signal does not return. If there is precipitation, the water droplets reflect the signal back to the radar detector. The time it takes for the pulse echo to return is related to the distance the droplets are from the radar; the brightness of the echo is related to the amount of precipitation. Radar signals are overlaid on surface maps to show location and colored to show intensity.

Question 13

What measures wind speed and direction?

Answer 13

Anemometer: Anemometers have cups attached to metal arms that are connected to a central post. Winds cause the cups to spin, and the spin rate is related to the wind speed
Doppler radar: uses radio signals to determine wind speeds in storms. Like the pitch of a siren changing as the ambulance moves past you, the frequency of the radio echo changes slightly as the droplets move toward (frequency increases) or away from (frequency decreases) the detector. The extent of the change, called phase shift is related to the wind speed; the direction of the shift is related to wind direction.

Question 14

What measures the heights of clouds, and how does it work?

Answer 14

Ceilometers: A pulsed laser beam is pointed skyward. When the beam hits the clouds, the light gets scattered by some of the particles in the cloud and is reflected back to the ceilometer. The distance is computed from the time delay between the pulse and the scattering of the light.

Question 15

Weather balloons and satellites

Question 16

What do surface weather maps contain?

Answer 16

Temperature data, precipitation, barometric pressures

Question 17

What are fronts, and what are the different types?

Answer 17

Boundaries between two air masses.
Warm front (red semicircles): Warm air mass displaces cool air mass
Cold front (blue triangles): Cool air mass displaces warm air mass
Occluded front (purple semicircles and triangles): cool air masses sandwich a warm air mass
Stationary front (red semicircles and blue triangles): Warm and cool air masses eet without overtaking each other; the blow in parallel but opposite directions
Trough (dashed line): Elongated area of low pressure

Question 18

What weather occurs at each front?

Answer 18

Warm front - Long lived, steady, light rain, followed by warm rain
Cold front - Short lived, thunderstorm, heavy rains followed by cooler temperatures
Occluded front - The warm air aloft causes heavy precipitation, and cooler air follows the front
Stationary front: Clouds form on both sides, without precipitation

Question 19

What can cause moist air to rise?

Answer 19

Orographic uplift: Airflow confronts a mountain barrier, air rises
Frontal wedging: Warm, moist air rises over cold, dense air
Convergence: Two airflows collide head-on, forcing air upward
Localized convection: Areas of the ground heat unevenly, and small pockets of hot air above the hot spots rise

Question 20

How are clouds formed?

Answer 20

Cooling most air condense around dust to form clouds

Question 21

What clouds do and do not make precipitation?

Answer 21

High clouds (cirrus, cirrocumulus, cirrostratus; above 20K ft) do not make precipitation
Midlevel clouds (altocumulus, altostratus; between 6K and 20K ft) can produce precipitation
Low clouds (stratocumulus, stratus, nimbostratus; below 6.5K ft) usually produce precipitation

Question 22

What is the different types of fog?

Answer 22

Radiation fog: ground cools rapidly, cools air immediately above it below the dew point, and a fog forms
Advection fog: warm, moist air blows over a cold surface
Upslope fog: Air rises along a mountain, fog forms like a cloud near the slope
Evaporation fog: when water vapor is added to air Steam fog occures when cool air moves over a warm body of water and picks up moisture to the point of saturation. With frontal or precipitation fog, after rain or snow at a front, the evaporating water will saturate the cold air above it and form fog.

Question 23

What are vertical development clouds, and what do they do?

Answer 23

Clouds that stretch over multiple altitudes within the atmosphere; lead to severe weather

Question 24

What is a midlatitude cyclone, how does it form, and where does it form?

Answer 24

Develops from a stationary front
A stationary front develops; upper air movements along the front cause a wave to form; At the point of the wave, warm air rises northward over the cold air and cold air sinks southward. The stationary front separates into cold and warm fronts; Air flows counterclockwise with a low pressure center (where the wave was established); the cold front catches up with the warm front to form an occluded front

Question 25

How do thunderstorms develop?

Answer 25

A cumulus cloud grows vertically upward into cumulonimbus clouds; updrafts of warm, moist air rise, cool, and condense to form water droplets; cold air sinks to replace the warm, moist air, producing downdrafts that create heavy precipiation, high wind, and hail

Question 26

How do tornadoes form?

Answer 26

They form in supercells, thunderstorms where updrafts rotate; ast upper-level winds and slow surface winds combine to form a tube of spinning air called a mesocyclone.Updrafts within the storm lift a loop of the mesocyclone and downdrafts break it into two parts, a clockwise-spinning part (toward the ground) and counterclockwise-spinning part (upward). The updrafts stretch the counterclockwise-spinning part, which forms a funnel.
When the funnel touches the ground, a tornado Opens in modal popup windowforms. The winds within the funnel are very high, the pressure is low, and a powerful suction develops. Tornadoes can last from seconds to an hour (most last about 10 minutes) and have diameters of 500–2,000 ft. Tornadoes are highly destructive storms.

Question 27

MHow do tropical cyclones form?

Answer 27

Tropical cyclones form when warm air blows over warm ocean water and picks up moisture, and convergence forces the air upward. As the air rises, it cools and condenses into water droplets.
The condensation process releases heat and warms the cool air aloft, which then rises even farther into the atmosphere. The whole process continually draws warm, moist air from the ocean to the atmosphere. The rising air decreases the pressure, begins to circulate counterclockwise around the low pressure center, and forms high winds associated with tropical systems.
The tropical cyclone continually feeds on warm ocean air and organizes into a tropical storm or hurricane Opens in modal popup window.

Question 28

Which sections of the country have the most and fewest tornadoes per year?

Answer 28

Most: Midwest/South
Least: West/Northeast

Question 29

Do tornadoes occur consistently during the spring and summer?

Answer 29

No

Question 30

What causes snowfalls?

Answer 30

Converging air masses, the same as the ones that spawn tornadoes

Question 31

Where do hurricanes occur?

Answer 31

US: Landfall on East and Gulf coasts
Atlantic OCeans, Caribbean Sea, GUlf of Mexico

Question 32

What hazards do thunderstorms bring?

Answer 32

Hail, lightning, high winds, tornadoes, and flash floods

Question 33

What hazards do tornadoes bring?

Answer 33

High damaging winds

Question 34

What hazards do hurricanes bring?

Answer 34

High damaging winds. storm surge, floods, and tornadoes

Question 35

What hazards do snow or ice bring?

Answer 35

Power failures and severe cold

Question 36

What hazards do floods bring?

Answer 36

High water, road hazards, and disease

Question 37

What does the National Weather Service do?

Answer 37

Monitors severe weather and issues severe weather watches and warnings