BBC Focus - 09.2019

Q&A

GETTY IMAGES X2, ALAMY ILLUSTRATIONS: DAN BRIGHT

NATRE’S WEIRDEST CREATRES...

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

prey goodjob.Thesechemicals

aractwatermolecules,sothey

havetheaddedbenefitof

keepingwaterlockedinthe

toothpaste,preventingit from

dryingout.Researchalso

suggeststhatxylitolcanhelpto

killoplaquebacteriain

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

alongtheseaoorusingitsfins

likefourlilelegs.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.Pued-uplikethis,

itsbodyvolumecanincrease

byasmuchas 30 percent.

Therearea coupleofpossible

reasonsforthisunusual

behaviour:it couldbea way

ofsavingenergyinan

environmentthat’slackingin

prey,andit couldalsohelpto

wardopredators,similarto

thepuerfish’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

hiing the ground

Storm

direction

HAIL FORMATION