Q&A
GETTY IMAGES X2, ALAMY ILLUSTRATIONS: DAN BRIGHT
NAT RE’S WEIRDEST CREAT RES...
DAVEFERRIS,LONDON
WHYDON’THAILSTORMS LAST AS LONG
AS RAINSTORMS?
Hailis producedduringthunderstorms,whenan
updraughtofwarm,moistaircarriestinydropletsof
waterupwards.Thedropletsfreezeathighaltitude,
andtheresultingicecrystalsgrowuntiltheyaretoo
heavytostaysuspended.Forhailtoform,a warmair
masshastomeeta muchcolderone(thisis what
creates the updraught). The hail only forms in a
narrowregionwherethesetwoairmassesmeet,
meaningthatit fallsoverjusta smallstripofland.
Thesehigh-energystormsalsotendtomovequickly,
sosomeoneonthegroundexperiencesthehailasa
shortburst.Finally,astheyneeda supplyofwarm,
moistairtofuelthem,hailstormsrelatively quickly
run out of energy and dissipate.AFC
Too t hp a s t ene e dss ome t hingt o
maskthesoapytasteofthe
detergentsthatcreatethefoam
whenyoubrush.Sugaris out,for
obviousreasons,butsweeteners
suchasxylitolorsorbitoldoa
pre y goodjob.Thesechemicals
a ractwatermolecules,sothey
havetheaddedbenefitof
keepingwaterlockedinthe
toothpaste,preventingit from
dryingout.Researchalso
suggeststhatxylitolcanhelpto
killo plaquebacteriain
themouthbystarving them
of sugar.ED
JOYCEBURLEY,HULL
WHYDOES
TOOTHPASTE
CONTAIN
SWEETENERS?
THE PINK FROGMOUTH
Holdontoyourbreath,dear
readers,forthismonthwe’re
divingdeep.Hundredsof
metresbeneaththesurfaceof
theworld’soceans,therelives
a curiousfishthatwaddles
alongthesea oorusingitsfins
likefourli lelegs.It hasa pink
complexionanda frog-like
mouth.Uponitsheadisa
unicorn-likedorsalfinwhich
glowsinthedarkandentices
inquisitivefishtotheirdoom.
Thisisthepinkfrogmouth,a
deep-seacreaturethatlooksto
havebeendesignedbya
sugar-addledsix-year-old.
Stillholdingyourbreath?
Good.Youandthepink
frogmouthhavethisin
common.Earlierthisyear,
scientistsdiscoveredthatthis
fish (and other members of its
taxonomicfamily)hasthe
uniqueabilityofholdingits
breathunderwater,foraslong
asfourminutes.
Fishbreathebyswallowing
oxygen-containingwaterand
pumpingit throughtheirgills,
wheretheoxygenisextracted.
Thepinkfrogmouth,however,
isabletoholdthiswaterinits
gillchamberswithout
exhaling.Pu ed-uplikethis,
itsbodyvolumecanincrease
byasmuchas 30 percent.
Therearea coupleofpossible
reasonsforthisunusual
behaviour:it couldbea way
ofsavingenergyinan
environmentthat’slackingin
prey,andit couldalsohelpto
wardo predators,similarto
thepu erfish’sdefence
mechanism.JH
Hail begins to form
Waterdropletsare
sucked into updraught
Warm updraught
Cold downdraught
Hailcirculates
and grows
Hailtooheavyforthe
updraughttoholdbeginsto
fall to the ground
Hailbeginstomelt,but
notcompletelybefore
hi ing the ground
Storm
direction
HAIL FORMATION