Chapter 5 Condensation: Dew, Fog, and Clouds

Question 1

what is the difference between dew and frost?

Answer 1

condensation on a surface at the ground is:
-dew (liquid)
-frost (frozen), temp below freezing

Question 2

why does dew and frost form at night?

Answer 2

nighttime cooling makes ground cold, accelerated by inversion (no clouds)

Question 3

what are the two different kinds of condensation nuclei?

Answer 3

hydrophobic-“water-repelling”
-oils, gasoline, waxes

hygroscopic-“water-seeking”
-salt, sulfuric and nitric acids

Question 4

how does haze occur?

Answer 4

in air, when RH is low T»Td “dry”, light scatters

RH 60-80%, more scattering
RH 75+% = some condensation (on “wet” hygroscopic nuclei), scatter white light

Question 5

what is fog?

Answer 5

as RH approaches 100%, haze particles grow larger and more condensation occurs. clouds near the ground (saturated air)

100% RH= fog (near ground) or clouds (above ground)

Question 6

what is radiation fog?

Answer 6

when earth radiates to cool itself, surface temp decreases, fog forms

-goes away after sunrise when no more nighttime cooling

T↓=Td RH=100%

Question 7

what is advection fog?

Answer 7

warm moist air move horizontally over a cooler surface (pacific coast, bay area)

T↓=Td RH=100%

Question 8

what is upslope fog?

Answer 8

moist air flows up a mountain (east of the rockies)

T↓=Td RH=100%

Question 9

what is evaporation fog?

Answer 9

warm moist surface provides enough moisture to saturate a dry air parcel (breath in winter)

Td↑=T RH=100%

Question 10

what are the 5 clouds terms?

Answer 10

cirro: high (ice), thin
alto: mid (mixed)
strato: low (liquid), blanket
cumulo: low (liquid), grows vertically
nimbo: precipitation

Question 11

what are the 3 high clouds?

Answer 11

all are high, thin, cold, ice

Cirrus: wispy
Cirrostratus: horizontally extensive
Cirrocumulus: vertical lumps

Question 12

what are the 2 middle clouds?

Answer 12

both mid-level base

altostratus: horizontal blanket
altocumulus: individual puffy clouds

Question 13

what are the 3 low clouds?

Answer 13

all low base, warm

stratus: thick blanket, blacks out sun
stratocumulus: horizontal coverage with breaks and vertical growth
nimbostratus: thick blanket, rain or snow

Question 14

what are the 2 lowest clouds?

Answer 14

both low base, grow vertically

Cumulus: individually puffy
Cumulonimbus: heavy precip, thunderstorms

Question 15

what is a lenticular cloud?

Answer 15

lens-shaped clouds that form as a result of atmospheric “waves” downwind of mountain ranges

Question 16

what is a banner cloud?

Answer 16

like lenticular but anchored to individual mountain peaks

Question 17

what is a pileus cloud?

Answer 17

like banner cloud but anchored to cumulonimbus towers

Question 18

what is a mammatus cloud?

Answer 18

lumpy on top and bottom, associated with very severe weather

Question 19

what is a jet contrail?

Answer 19

exhaust provides condensation nuclei and H2O vapor is added, it’s a real cloud

Question 20

where are nacreous clouds found?

Answer 20

stratosphere