Season Deproj

A se as on is one of th e ma jo r di visi on s o f th e y ea r gen era lly bas ed on ye ar ly pe ri odi c cha ng es in we athe r. In temp er atu re a nd po la r regio ns g ener al ly fo ur se as ons ar e reco gniz ed : spri ng , summ er , autum n ( fal l ), an d wi nte r. In so me t ro pica l an d su bt ro pica l reg io ns it is mo re co mmo n to spe ak of th e rainy (or wet, or m on so on) se as on ve rsu s the dry sea son , as the am ou nt o f pr ecipit atio n m ay v ar y mo re dram atic ally tha n the av er age t emp er atur e. In oth er tr opic al are as a thr ee -way di visi on int o hot , ra iny and c ool s eas on is us ed . In som e par ts of the wo rl d, sp eci al "s ea so ns " a re loo sel y d efin ed b as ed upo n impo rta nt ev en ts su ch as a hur ric an e se as on, to ron do se as on or a wi ld fir e sea son Seasons Temperate

Tropical

Spring

Cool Dry season

Summer

Autumn

Winter

Hot

Wet season

Dia gram of the Ear th's sea son s as see n fr om th e no rth. Fa r ri ght : De cemb er sol stic e

Dia gram of the Ear th's sea son s as see n fr om th e south. Far left : Ju ne so ls tic e

Fig. 1 This is a diagram of the seasons.

Re ga rdl es s o f the tim e o f day (i .e . the Ea rth 's rotati on on its ax is ), th e N orth P ole wil l b e d ark , an d th e S outh Pol e wil l be illumi nat ed ; see al so a rctic wi nte r. I n ad diti on to the den sity of inci de nt li ght, the di ssip atio n o f li ght in the atmo sphe re is gre at er whe n it f al ls at a s ha ll ow an gl e. The se as ons r esu lt fr om th e E ar th' s a xi s be in g tilt ed to it s o rbit al pl an e; it devi ate s by a n an gle o f app ro ximat ely 23.5 degr ees . Thu s, at any gi ve n time du ri ng th e s umme r or wi nte r, on e part of the pl an et is mo re di re ctly exp os ed to th e ra ys of the Sun ( see Fig .

1 ). T his exp osu re alt er na te s as the Ea rth revo lv es i n its orbit. At any gi ve n time, rega rdl es s o f sea so n, the no rthe rn a nd south er n hemi sphe re e xpe rie nc e opp osit e sea so ns (s ee Fig . 2 an d Mon th ran ges of se as ons ( bel ow) and E ffe ct of s un a ng le on clim ate ). Sea so na l weath er f luctu atio ns a ls o dep en d on fact or s su ch a s pro ximity to oce an s or o th er l arg e bodi es of wat er , cu rre nt s in tho se o cea ns , El Nin o/ EN SO an d oth er oc ea ni c c yc le s, and p re vai lin g win ds . In the te mpe rat e an d pol ar regi on s, s eas on s are ma rk ed by cha ng es in the am ou nt o f sun light, whi ch in tur n of te n cau se s cy cl es o f dorm ancy in p la nts an d hib er na tio n i n a nim als . The se ef fe cts var y with latitud e, and with pro ximity to bod ie s of w ate r. Fo r exa mple , the South P ole is in the mid dl e of th e co nti ne nt of Anta rc tica , a nd the re fo re a co ns id er abl e di sta nc e fr om th e m od era tin g influ en ce of th e south er n oc ean s. Th e North Pol e is i n th e Ar ctic Oce an , an d thus it s t empe ra tur e ext re me s ar e bu ffe re d b y the pre se nc e of al l that wat er . Th e res ult is that the S outh Pol e is con si ste ntly col de r du rin g the south er n wint er th an th e N orth P ole du ri ng th e no rthe rn wi nte r.

Fig . 2 As th e Ea rth rev ol ve s aro un d the Sun , the sea son s in the north er n an d south er n hemisph er es a re oppo site . The c yc le of se as ons in the po la r and t empe ra te zon es of o ne hemisphe re is opp os ite to that in the othe r.

Whe n it is s umme r in th e N orthe rn hemisph er e, it is wint er i n the South er n Hemisph er e, a nd vic e ve rsa , an d wh en it is sp rin g in th e N orthe rn h emisph er e it is autum n i n th e South er n hemi sphe re , and vi ce v ers a. I n th e tr opic s, th er e is no noti ce ab le c ha ng e in the am ount of su nli ght. Ho we ve r, many regi on s (f amo us ly the north er n In di an Oce an ) ar e s ub je ct to m on so on ra in and wi nd c yc le s. Cu rio us ly, a st udy of temp er atu re r ecor ds ov er th e p ast 300 ye ar s (D avi d Tho mps on , Sc ie nc e, Ap ril 1995) show s that the clim atic se as ons , an d thu s the sea so na l, a re gove rn ed by th e a noma listi c y ea r rath er th an the t ro pica l ye ar . In met eo rol ogic al te rm s, th e wi nte r sols tice and summ er s ols tice ( or th e da te ma ximum/mi nimum in sulati on ) do not fall in th e mi dd le of wint er a nd summ er r esp ecti ve ly. Th e h eig hts of the se sea son s oc cu r up to a month late r due to se as ona l la g. Sea so ns thou gh, are not al way s de fin ed in met eo rol ogic al te rm s. Co mpar ed to a xi al tilt, othe r fact or s con tri but e l ittl e to sea son al t empe ra tur e ch an ge s. I t' s a commo n misc on ce ptio n that the sea so ns are th e res ult of the va riati on i n E ar th’ s di sta nce t o the sun due to its el liptic al orbit. Orb ital ecc en tr icity ca n inf lue nc e temp er atu re s, b ut on Ea rth , thi s e ff ec t i s s ma ll an d i s mo re than cou nte ra ct ed b y oth er fa cto rs ; r esea rc h sh ow s th at the Ea rth as a wh ol e is ac tual ly a fe w deg ree s w ar me r whe n fa rth er f rom the sun Mar s ho wev er ex pe ri en ce s wid e temp er atu re va riati on and vio le nt du st st orms e ve ry y ea r at p er ihe lio n

The d at e at which each of the fou r temp er at e se as on beg in s v ar ie s fr om cultu re t o cu ltur e. I n gene ral th er e ar e th re e reck oni ng s, " Ast ro nomic al", "Met eo rol ogi cal" , a nd "T ra ditio na l"

Month ranges of seasons Traditi on Winter Spring

Months Meteorol Astrono (North/Sout ogy my h) Winter

Jan /Ju l Winter

Spring

Fe b/ Au g Mar /Se p Apr /Oct

Summer

Spring Summer

May /N ov Ju n/ De c Jul /J an

Autumn

Summer Autumn

Aug /Fe b Sep/ Mar Oct /Ap r

Winter

Autumn Winter

Nov /M ay De c/J un

I n h emib or eal and temp er ate c limat es :

In the wint er , the pla nt ca n't ho ld th e le av es without Chl or yphyl l.

In th e In the autum n, In the sp ri ng , summe r the the tre es st op plant s grow . maki ng the pl ant s Usual ly at Chl or yphyl l a nd pr od uc e tur n ye ll ow or Chl or yphyl l thi s tim e sh ad es o f an d sta rt to th e pla nts grow agai n. comp let ely ora ng e a nd red matur e. the n dro p th eir le av es .

In as tr on omi cal reck oni ng , the sea son s begin at th e as tr on omi ca l s ols tice s an d equin ox es . Th e cr oss qua rte r day s ar e th e midp oint s o f th e A st ro nomic al se as ons . Th e le ng th of th es e sea so ns is not unif or m bec aus e of the el liptic al orbit of th e ea rth a nd its dif fe re nt sp ee ds al on g th at o rbit. In the con ve nti on al US cal en da r, •

Wint er ( 89 d ays ) b egi ns on 20 -23 D ec, th e wint er sol stic e, • Sp ri ng (92 d ay s) o n 19 -22 Ma r, th e spri ng equi no x, • Summ er (93 da ys ) on 19-23 Jun e, th e s umme r sol stic e, an d • Autumn (90 d ay s) o n 21 -24 Sept, th e autumn equi no x. An d, th e cr oss -qua rte r day s a re con si de red s eas on al midp oint s, •

Wint er : 5-10 N ov (Samh ain , 立冬) • Sp ri ng : 2-7 Feb ( Im bo lc , 立春 ) • Summ er : 4 -10 May (Be lta ne , 立夏 ) • Autumn : 3- 10 Au g (Lugh na sa dh , 立秋 )

The f ou r sea so n mah jo ng tile s on the right and the fo ur flo we r til es on th e oth er s id e. T he flo we r til es ar e a rra nge d in a cc ord to th eir growi ng s eas on s.

Per son ificati on s of the Fo ur S eas ons a re a fre que nt them e in Ro ma n m os aic s, lik e this fr om C omp lutum. Tr ad itio na l s eas on s a re rec ko ned b y in so lati on , with summ er b ein g the qua rt er o f the y ea r with the gre at es t i ns ol atio n, and wi nte r th e quar te r with the le as t. Th es e sea so ns beg in ab out 4 wee ks earli er than

the Mete oro lo gica l se as ons , an d 7 we ek s ea rli er th an the Astr on omica l s eas on s. In Tr ad itio na l r eck on in g, th e s eas on s begi n a t the cr oss - qu ar te r da ys . The s ols tice s an d e quin ox es ar e the mi dpoi nts of the se sea son s. F or examp le , the day s of g reat est and l ea st ins ol atio n ar e con si de red the "midwi nte r" an d "mid summe r" respe ctiv ely . This reck oni ng i s us ed by va rio us tra ditio na l c ultu re s in the North er n Hemisph er e, i nc ludi ng East Asia n a nd Iri sh c ultu re s. So, a cc ord in g to T ra diti on al reck oni ng , •

Wint er b egi ns on 5-10 N ov, Samh ain , 立冬 (l ìd ōn g), • Sp ri ng on 2-7 Fe b, Imb ol c, 立春 (lì chū n) , • Summ er on 4-10 May , Be lta ne , 立夏 (l ìx ià) , an d • Autumn on 3-10 A ug , Lugh na sa dh , 立秋 (l ìqiū ). An d, th e mid dl e of eac h s eas on is co nsid ere d, •

Mid -wi nte r: 20-23 Dec , wint er s ols tic e, 冬至 (d ōn gzhi) • Mid -s pri ng : 19 -22 M ar , sp rin g equi no x, 春分 (c hū nfē n) • Mid -s umme r: 19-23 Ju ne , summ er s ols tice , 夏至 (x iàzh ì) • Mid -a utumn: 21 -24 Sept , autumn equi no x, 秋分 (qiū fē n)

The

Ea rth' s sea so ns ar e n ot c au se d by th e diff er enc es i n the dist anc e fr om th e Su n thr ou gho ut th e ye ar ( the se dif fe re nc es ar e e xtr eme ly sm al l) . T he sea so ns are th e res ult of the tilt of the Ea rth 's axis . The E ar th' s a xi s is tilt ed fro m pe rpe nd icul ar t o the pla ne o f th e e cl iptic by 23.45° . T his tiltin g is wh at gi ve s us the fou r se as ons of th e ye ar - sp rin g, summ er , autum n ( fa ll ) an d wi nte r. Sin ce th e axi s is tilte d, d iff er en t pa rts of the glob e are ori ent ed to wa rd s the Sun a t d iff er en t time s o f th e y ea r. Summ er is wa rm er th an wint er (i n e ac h hemisph er e) bec aus e the Sun 's ray s hit th e Ea rth at a mor e dir ect an gl e dur in g summ er th an du ri ng wi nte r an d als o bec aus e the day s ar e mu ch l on ger tha n the ni ghts du ri ng th e s umme r. D ur in g the wint er , th e S un 's r ays hit th e Ea rth at an ex tr em e an gl e, an d the day s ar e ve ry sho rt . T he se e ff ect s are d ue to th e ti lt o f th e Ea rth' s ax is .

Solstices The s ols tice s are da ys wh en th e S un r eac he s its fa rth est north er n an d south er n dec li nati on s. Th e wint er s ols tic e o ccu rs on Dec em be r 21 or 22 an d ma rk s th e beg in nin g of wi nte r (thi s is the sho rt est day of th e ye ar ). T he summe r sol stic e oc cu rs o n J un e 21 an d ma rk s the begi nnin g of summ er (this is th e lo nge st day of the ye ar ).

Equinoxes Equin ox es ar e day s in which da y an d ni ght ar e o f

equ al du ra tio n. Th e two y ea rl y e quin ox es oc cu r whe n the Sun c ross es the cel es tial equat or . The v ern al equin ox occ ur s in late M ar ch (thi s i s the beg in ning o f spri ng i n th e North er n Hemi sphe re an d the begin nin g of f al l in the Southe rn H emisph er e); the autum nal equin ox occ ur s in la te Septem be r (this is the beg in ning o f fal l i n th e North er n Hemi sphe re an d the beg in ning o f spri ng i n th e South er n He misph er e) .

Presented and Prepared By :Mrs. Ranbir Kaur S.S. Mistress G.G.S.S. Kot Baba Deep Singh, Amritsar.