CHAPTER 7

CLOUDS, PRECIPITATION, AND WEATHER RADAR
____________________________________________________

MULTIPLE CHOICE QUESTIONS

 1.	The activation temperature of most ice-forming nuclei is ______ 0 oC.
	a.  above            		b.  about     			c.  well below

 2.	Hygroscopic nuclei ______ water molecules.
	a.  repel                		b.  attract		  	c.  vaporize

 3.	Hygroscopic nuclei
	a.  have numerous natural and human-related sources.
	b.  are relatively abundant downwind of urban-industrial areas.
	c.  favor cloud formation at relative humidities under 100%.
	d.  All of the above are correct.
	e.  None of the above is correct.

 4.	The relative humidity within a cloud is ______ 100 percent.
	a.  much less than     		b.  about     		 	c.  much greater than

 5.	The British naturalist who is credited with being among the first to devise a classification of cloud types is
	a.  Benjamin Franklin.        			d.  Sir Isaac Newton.
	b.  Stefan-Boltzmann.         			e.  Charles Boyle.
	c.  Luke Howard.

 6.	A cloud that develops as a consequence of local convection is 
	a.  stratus.                  				d.  nimbostratus.
	b.  cirrus.                  				e.  cumulus.
	c.  cirrostratus.

 7.	Which one of the following cloud types would most likely be responsible for producing heavy rain?
	a.  cumulus                   			d.  cirrocumulus
	b.  cumulonimbus              			e.  cirrus
	c.  altocumulus

 8.	A cloud that forms when warm air overrides cold air is 
	a.  cumulus.                  			d.  cumulus congestus.
	b.  cumulonimbus.             			e.  None of these is correct.
	c.  cirrostratus.

 9.	A cloud that exhibits considerable vertical development is
	a.  fair-weather cumulus.		  	d.  cirrus.
	b.  altostratus.		    			e.  cumulonimbus.
	c.  stratocumulus.
 
10.	All of the following clouds typically have relatively low bases with the exception of
	a.  cirrus.                   				d.  fog.
	b.  stratus.                  				e.  nimbostratus.
	c.  stratocumulus.

11.	Which one of the following clouds is most likely composed of ice crystals only?
	a.  stratus                   		           		d.  nimbostratus
	b.  cumulonimbus              			e.  altocumulus
	c.  cirrus

12.	A mountain-wave cloud:
	a.  noctilucent               			d.  cumulonimbus
	b.  stratus                     			e.  nacreous
	c.  altocumulus lenticularis

13.	A rarely seen cloud that forms in the mesosphere and may be composed of ice deposited on meteoric dust:
	a.  noctilucent               			d.  cirrus
	b.  nacreous                  			e.  aurora borealis
	c.  altocumulus lenticularis

14.	All of the following clouds may be formed by waves propagating horizontally within the atmosphere with the exception of _____.
	a.  altocumulus lenticularis  		  	d.  cirrocumulus
	b.  altocumulus             			e.  stratus
	c.  stratocumulus

15.	Of the following cloud types, which one is coldest?
	a.  cirrus                    				d.  altocumulus
	b.  stratus                   				e.  fog
	c.  cumulus

16.	Of the following cloud types, which one is warmest?
a.  cirrus
b.  cirrostratus
c.  cirrocumulus
d.  altostratus
	e.  stratus

17.	Condition(s) required for extreme nocturnal radiational cooling is (are)
	a.  clear skies.              			d.  All of these are correct.
	b.  strong winds.             			e.  None of these is correct.
	c.  high vapor pressure.

18.	Condition(s) required for extreme nocturnal radiational cooling is (are)
	a.  clear skies.              			d.  All of these are correct.
	b.  light winds or calm conditions.             	e.  None of these is correct.
	c.  low vapor pressure.

19.	In dense fog, the mixing ratio is ______ the saturation mixing ratio.
	a.  much less than    		b.  about equal to   		c.  greater than

20.	Fog formed when warm humid air streams over the cold surface of a lake is known as
	a.  radiation fog.             			d.  sea smoke.
	b.  steam fog.                			e.  advection fog.
	c.  upslope fog.

21.	Fog formed when cold dry air streams over the surface of a relatively warm body of water is known as
	a.  radiation fog.            			c.  mist.
	b.  upslope fog.           				d.  steam fog.

22.	A likely site for development of persistent radiation fog is a
 	a.  hilltop.                  		           		d.  mountain summit.
	b.  river valley bottom.     			e.  None of these is correct.
	c.  valley slope.

23.	Cold air is ______ warm air and ______.
	a.  less dense than.......  ........tends to rise
	b.  more dense than...............flows downslope

24.	The type of fog formed in spring when mild humid air flows over an old snowcover is
	a.  radiation fog.           			d.  advection fog.
	b.  steam fog.                	  		e.  upslope fog.
	c.  arctic sea smoke.

25.	Source(s) of condensation nuclei:
	a.  forest fires              		  		d.  industry and agriculture
	b.  wind erosion of soil     			e.  All of these are correct.
	c.  seawater spray

26.	Mountain waves
	a.  are stationary.
	b.  are usually associated with prominent mountain ranges.
	c.  may produce altocumulus lenticularis clouds.
	d.  All of the above are correct.
	e.  None of the above is correct.

27.	The convective condensation level (CCL) closely corresponds in altitude to the base of a ______ cloud.
	a.  cirrostratus			           		d.  altostratus
	b.  cumulonimbus				e.  cirrus
	c.  altocumulus

28.	Which one of the following has the greatest terminal velocity?
	a.  ice crystal					d.  raindrop
	b.  drizzle drop              			e.  snowflake
	c.  hailstone

29.	For a given particle, the terminal velocity is greater in ______ than in ______.
	a.  water.....air            				b.  air.....water

30.	Most precipitation that falls in midlatitudes originates in ______ clouds.
	a.  cirrus                    			d.  altostratus
	b.  cumulus                   		e.  stratus
	c.  nimbostratus or cumulonimbus

31.	Most precipitation that falls in midlatitudes originates in ______ clouds.
	a.  warm                     			b.  cold

32.	It takes about ______ cloud droplets to form a single raindrop.
	a.  100                         			d.  100,000
	b.  1000                     			e.  1,000,000
	c.  10

33.	A warm cloud is composed of
	a.  tiny water droplets.
	b.  ice crystals.
	c.  a mixture of ice crystals and supercooled water droplets.
	d.  supercooled water droplets.
	e.  None of the above is correct.

34.	The following is most likely to be a warm cloud:
	a.  cirrus				d.  cirrocumulus
	b.  cirrostratus				e.  altostratus
	c.  stratus

35.	A cold cloud is composed of 
	a.  ice crystals.
	b.  supercooled water droplets.
	c.  a mixture of ice crystals and supercooled water droplets.
	d.  Any of the above is correct.
	e.  None of the above is correct.

36.	An example of a cloud that is always cold is 
	a.  cirrus.                   			d.  fog.
	b.  stratus.                  			e.  stratocumulus.
	c.  cumulus.

37.	A cloud that may be cold at the top and warm at low levels:
	a.  cirrus				d.  cirrostratus
	b.  cirrocumulus			e.  stratus
	c.  cumulonimbus

38.	Clouds at temperatures between 0 and -9 oC are typically composed of 
	a.  ice crystals only.
	b.  a mixture of supercooled water droplets and ice crystals.
	c.  supercooled water droplets only.
	d.  None of the above is correct.

39.	Cumulonimbus (thunderstorm) clouds typically are
	a.  cold clouds.
	b.  warm clouds.
	c.  cold at high altitudes and warm at low altitudes.
	d.  None of the above is correct.

40.	At saturation and at the same temperature, the vapor pressure is greater over ______ than over ______.
	a.  ice...............water            		b.  water................ice

41.	The collision-coalescence process occurs in ______ clouds.
	a.  cold      	 	b.  warm             c.  cirrus      	    d.  altocumulus

42.	In cold clouds, a vapor pressure that is ______ for water droplets is ______ for ice crystals.
	a.  saturated...............saturated
	b.  saturated...............unsaturated
	c.  saturated...............supersaturated
	d.  supersaturated...............saturated

43.	Drizzle may be produced by ______ clouds.
	a.  nimbostratus			d.  cirrus
	b.  stratus				e.  cirrostratus
	c.  altocumulus lenticularis

44.	The type of frozen precipitation sometimes produced by a summer thunderstorm is
	a.  snow.                    			d.  hail.
	b.  freezing rain.            	  	e.  sleet.
	c.  snow pellets.

45.	On average, the meltwater equivalent of 100 cm of fresh snowfall is ______ cm.
	a.  1              		           		d.  20
	b.  10              				e.  0.1
	c.  100

46.	Weather radar continually emits pulses of _________.
	a.  sound waves.
	b.  X-rays.
	c.  gamma rays.
	d.  microwaves.
	e.  visible light.

47.	Operating in the Doppler mode, weather radar detects particles moving 	__________ the radar beam.
	a.  perpendicular to			b.  directly toward or away from

48.	Weather radar gathers information about precipitation in clouds by measuring the
	a.  energy emitted by the precipitation particles.
	b.  absorption characteristics of falling precipitation.
	c.  amount of energy scattered back to the transmitter.
	d.  amount of sunlight reflected off the falling precipitation.

49.	Doppler radar measures the following in addition to those quantities measured by 	conventional reflectivity radar:
	a.  the speed of targets toward or away from the station
	b.  the speed at which precipitation particles are falling
	c.  the average size of the precipitation particles
	d.  the type of particle, whether rain or snow

50.	Weather radar displays show the
	a.  intensity of the return at the proper direction and distance.
	b.  intensity of the return at the proper height and distance.
	c.  the character of the returning signal, whether precipitation or ground clutter.    
	d.  All of the above are correct.