202307

Cervencove pokracovani meho minuleho, cervnoveho blogu o pocasi https://laengsfelds.blogspot.com/2023/05/202305.html . Srpnovy blog o pocasi v Podkrkonosi je zde

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1. - 6. srpna. Zacina postupne cim dal vic prset.. Podivejume se tedy pro kontrast na jezero Ounianga uprostred Sahary v severnin Cadu. Tam rocne spadne min, jak 10 mm srazsek. Pozn. Tenhle prispevek byl sice taky puvodne motivovan politicko ukrajinsky - chtel jsem se jen na portalu mapy.cz podivat na zemi zvanou Niger, kde ted pry provolavaji slavu Poutinovi a kam se pry tez chystaji Prigozinovi zoldneri... ale upoutala mne natolik ta obrazova nadhera saharske krajiny, ze jsem si hned shromazdil nevelke album vyrezu z tohoto portalu https://photos.app.goo.gl/aR5wSHRt84g114GF8 Nektere z tamnich nejvyznacnejsich lokalit jsou popsany v nasledujicich odkazech a vypiscich. I maly uryvek z clanku o saharskych krkokodylech doklada, jakou tupou demagogii je soucasna oteplovacska ideologie, kterou media a politici chrli jiz treti desetileti - a oc zajimavejsi a dramatictejsi je skutecna historie klimatu. Prectete si pozorne treba jen tyhle dve vety:

V době posledního glaciálního maxima (18 000 let) byla Sahara mnohem větší a teplejsi než dnes, ale v polovině holocénu (7 000 let) poust v důsledku vyšších teplot a srážek ve srovnání se současností téměř zmizela. Během této poslední humidní fáze byly vyprahlé pláně a písečná moře nahrazeny do znacne miry jezery, travnatými plochami a otevřenými savanami .

(A male zbytky one davne, "petitisicilete" vody jsou pricinou dodnes existujicich, nekdy na prvni pohled az neuveritelnych oaz uprostred te ohromne pouste.)

Odkazy, ktere stoji za to si v teto souvislosti precist: https://en.wikipedia.org/wiki/Lakes_of_Ounianga https://www.atlasobscura.com/places/guelta-darchei https://en.wikipedia.org/wiki/Barda%C3%AF,_Chad https://en.wikipedia.org/wiki/Ghat,_Libya https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3045445/

The Sahara is the largest desert in the world and it is characterised by the occurrence of vast dune fields and featureless plains subjected to low precipitation levels and high temperature ranges . However, this apparently bare ecosystem has not always been like this. Since the onset of the Sahara, at about 7 M.Y.A its range has largely fluctuated following closely periodical climatic oscillations. Several alternated phases of dry and humid climates have occurred allowing the expansion and contraction of the desert areas, respectively, through range shifts of the hyper-arid sand seas and featureless plains. At the Last Glacial Maximum (LGM, 18,000 yr), the Sahara was much larger and warmer than today, but during the mid-Holocene (7,000 yr) it was almost absent due to the higher levels of temperature and rainfall in comparison with the present day. During this last humid phase, the arid plains and sand seas were replaced by lakes, grasslands and open savannas in many low altitude sites, and temperate xerophytic woods and warm mixed forests covered mountains.

Desert Lakes of Ouianga. Geography.Water accumulated in an underground aquifer during the wet millennia is supplied to the lakes. When water is exposed at the surface in highly arid environments it becomes saline due to a high rate of evaporation as is the case with the lakes of the Ounianga Kébir group. The rate of evaporation from Lake Yoa is equivalent to 6 metres a year and the total lake depth is 25 metres. (Pozn. U Kaspickeho more je to zhruba jeden metr - muzete sami overit porovnanim jeho plochy a udajem o prumernem prutoku Volhy (ktery vynasobme 1,5 abychom zapocetli dalsi pritoky i srazky primo na hladine toho more.) The lakes of the Ounianga Sérir group form a hydrological system that is unique in Earth’s deserts. Unique physical factors combine to keep all of the lakes fresh, except the central Lake Teli. Wind blown sand separated the basin into 10 lakes with Lake Teli occupying the central position. Thick mats of reeds cover the surface of the smaller fresh water lakes where they slow evaporation, but are absent from the saline waters of Lake Teli. As a result, greater evaporation takes place from the surface of Lake Teli, keeping its water level lower. This allows water rom the adjacent lakes to flow through the permeable dune barriers into Lake Teli keeping their waters fresh.

Panorama of Sérir.Connection to the history of humanityThe climatic history of the region is speculated to have a connection to human migrations at the end of the last ice age about 11,000 years ago. The desert returned to the area after monsoons diminished about 5,000 years ago. Investigation of a drilling core revealed 10,940 layers in 16 metres (52 ft) of sediments from the bottom of the Lake Yoa before reaching the ice-age desert floor, each layer corresponding to 1 year.[4] There is aerial photographic evidence that shows early human settlers of the lakes attempted to stop the desertification that inevitably inundated their orchards and crops. During the African humid period the early humans found the freshwater lake area to be fertile enough to grow crops and may have also domesticated cattle. Rock art found in many areas of the Sahara attest to that. However, a change in the climate slowly and eventually led to drought that continues to this day. As the desert wind from the northeast blew, it carried sand from the plateau above down through notches in the land, depositing it right where farmers were growing crops. Seeing that the sand would eventually smother their crops and orchards the lake dwellers attempted to stop it by erecting barriers. These barriers can be seen in aerial photographs at several places among both Ounianga Kébir and Sérir. They appear as series of “V’s” like this: VVVVVV with some as long as 2,300 feet across and in rows. The effort appears to be extraordinary for it would have required many people to erect the many layers of barriers that can be seen today. Unfortunately these “fences” failed and sand eventually claimed the area driving out the settlers anywhere between 7,500 and 5,000 years ago

Tahle poznamka nize o libyjskem meste Ghat je taky dobra, ukazuje ze na Sahare se kupodivu opravdu asi casteji umira utopenim - nez smrti zizni, plus vybizi i ke kritickemu zamysleni se nad pouzivanim - nejen tady - toho slova "average" neboli "prumer" : ) Annual precipitation averages only 8 mm (0.32 in) making the location one of the driest places on Earth. The sky is always clear and bright throughout the year. Nevertheless, in June 2019 there were heavy downpours which caused great damage to the town. Thousands of residents were stranded and few were reported dead or missing

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29. cervence. Konecne leto jak ma byt - teplo a vecer s kratkym sice, ale poradnym slejvakem. Hezke odpoledni mraky na Kozakove. V Brode byla, koukam nejaka neckyada a zaprselo i v Jizerkach

Pripravujeme novou kameru hydronetu v Korenove. Pokud by nekdo hledal kratky adrenalinovy prazdninovy zazitek - nabizim moznost spoluucasti na pokusu o vycisteni - z koryta reky - zvenci velmi zaspineneho okna :)

26.7. Cteni o pozarech ve Stredomori https://neviditelnypes.lidovky.cz/spolecnost/pozary-horici-koruny-a-dute-hlavy.A230725_165535_p_spolecnost_nef https://www.parlamentnilisty.cz/arena/rozhovory/-Ne-zmena-klimatu-Jinak-Pozary-Drtive-vysvetleni-jde-i-o-EU-740212. Fakt je ze z ekomedii letos zmizely clanky - drive pomerne caste - o blahodarnosti pozaru pro ekologickou diversitu chranenych uzemi nebo treba - take - o tom, ze biotopy zatopene ohromnymi stalinskymi prehradami v SSSR byly vlastne ekologicky mnohem bohatsimi, zajimavejsimi a cennejsimi nez ta rozsahla prehradni jezera, ktera tam bolsevik vyubudoval

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Skoda ze do takove kroupy se neda instalovat nahravaci zarizeni, zaznamenavajici zpetne :) jeji vznik, rust a pad . To by byla panecku podivana - do deni uvnitr turbulentniho mraku :)

25. cervence. Pres docasne vlny tepla se dale ochlazuje, prave leto v udolich Podkrkonosi je uz asi pryc :) Naopak v jizni Evrope jsou vrcholna vedra, na Sicilii vidime ted +40 a v Apulii v 850 hPa tedy ve vysi Snezky skoro +30. Naopak severne od Skotska klesa teplota v 850 hPa pod nulu

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22.7. Ochladilo se, pocasi se dnes vratilo ke stavu, jak typicky byvalo o prazdninach pred desetiletimi. Vedro ve Stredomori ale pomerne chladno v zapadni a stredni Evrope. Velke vedro pretrvava v jizni Italii a na Balkane, je tam ted skoro o 20 stupnu tepleji nez u nas

19. cervence. Rano noctilucentni oblaka na Kamenci. Posledni roky jsou tahle NLC oblaka opet spis vzacne - v porovnani s ne tak davmymi lety, kdy byly castejsi a vyraznejsi

17.7. Doznivajici "slunovrati" podvecerni zadni osvetleni zaberu korenovske kamery

17. 7. Nizke vodni stavy

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K ranu trochu zaprselo

16. cervence. Kupodivu se docela ochladilo a k ranu zaprselo, predvidane rekordy se dnes uz konat nebudou

15. cervence. Velmi teply den https://www.novinky.cz/clanek/pocasi-meteorologove-zprisnili-vystrahu-40437860

13. cervence. Pohled na teploty prvni poloviny cervence

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U rekordniho tepla je tohle vzdycky jasne, u rekordniho chladu nikoliv :) https://www.novinky.cz/clanek/zahranicni-v-johannesburgu-poprve-za-vice-nez-deset-let-napadl-snih-40437303 Mnoho lidí v Johannesburgu v pondělí vypadalo, že je vzácný pohled na zasněžené ulice potěšil. „Šli jsme to s dětmi prozkoumat,“ řekla BBC učitelka základní školy Agnes Midevová... Zatím není jasné, jestli ve vzácné sněhové nadílce v Johannesburgu hrály nějakou roli klimatické změny, dodala BBC

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8.7. Pohled na teploty. Zda se ted - zatim - ze moznou charakteristikou nakonec i tohoto leta bude "horke a suche". "Evergreenem" poslednich 10 let je take stojata voda v nahonu v Brode (viz graf teploty tamni vody) cili voda nevhodna ke koupani. Sice tepla ale ne moc cista, a pokud budou srazky jen ve forme mistnich bourek bude voda v Jizere jeste spinavejsi. Koukam, ze Povodi meni zpusob zobrazovani prutoku je to mnohem osklivejsi ale mozna poctivejsi a vernejsi nez drive, nevim http://www.pla.cz/portal/sap/cz/PC/Mereni.aspx?id=32&oid=1 co mne ale vzdycky udivuje pri takovemto suchu a slunnem (to je podmiinkou) pocasi je zaznam hladinomeru z Jezdecke nad Sousi, kde neni naprosto zadne antropogenni ovlivneni prutoku. Delaji to ale i mnohe ine podobne stanice a asi to bude objektivni vypoved o vlastnostech prislusnych meridel. Nebo dokonce o fluktuacich intensity pramenu pri takovemto pocasi? To druhe nejspis tedy ne (ze by tedy napr. pouha tepelna roztaznost vody? nebo meridla? :) ale nevim http://www.pla.cz/portal/sap/cz/PC/Mereni.aspx?id=181&oid=1 Jinak ten (velmi) priblizny pomer prumernych prutoku, co jsem tak behem let odpozoroval 1:10:80 na Cerne Desne - Jezdecke, v Mumlave a v Brode plati vicemene i ted

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Tohle si sem davam jen pro rychle nalezeni odkazu, ekolist nektere clanky s hojnou a pro mne zajimavou diskusi rad casem schova tak, ze da praci je vyhledat https://ekolist.cz/cz/zpravodajstvi/zpravy/soubeh-extremnich-klimatickych-jevu-v-ruznych-castech-planety-znepokojuje-vedce

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6.7. Zajimavy pohled na teploty tesne pred vrcholem leta v Eurasii. Vicemene stale jeste vetsinou zamrzly je severni ledovy ocean, na druhe strane uvnitr Sibire je samozrejme jiz nekolik tydnu teplo, aktualne napr. na soutoku Obu a Irtyse +30. V okolil Pekingu vidime skoro +44 zatimco severovychodni pobrezi Spanelska ma po ranu jen +14 a Irsko +11. V centralnim Gronsku je az -17 stupnu

5.7. Kolik holubu je na tomto snimku? :) Zatimco v Holandsku radi dnes rekordne silna letni boure tak u nas jsou vetsinou spis jen drobne prehanky - a celkove je opet znacne sucho