{"id":461,"date":"2018-02-07T09:00:00","date_gmt":"2018-02-07T08:00:00","guid":{"rendered":"http:\/\/vandiepenbeeck.org\/?p=461"},"modified":"2018-02-07T09:00:00","modified_gmt":"2018-02-07T08:00:00","slug":"les-facteurs-qui-influencent-le-climat-partie-26","status":"publish","type":"post","link":"http:\/\/vandiepenbeeck.org\/?p=461","title":{"rendered":"Les facteurs qui influencent le climat – partie 26"},"content":{"rendered":"

La circulation g\u00e9n\u00e9rale (2)<\/span> <\/span><\/p>\n

<\/p>\n

Les cons\u00e9quences de la circulation atmosph\u00e9rique g\u00e9n\u00e9rale sont les brassages des masses d\u2019air. Il en r\u00e9sulte que la temp\u00e9rature moyenne en fonction de la latitude est plus \u00e9lev\u00e9e que la temp\u00e9rature th\u00e9orique (sans brassage). Cet effet est plus marqu\u00e9 dans l\u2019h\u00e9misph\u00e8re Sud \u00e9tant donn\u00e9 la pr\u00e9sence plus importante d\u2019oc\u00e9ans.<\/p>\n

Tableau 1 : Valeurs des temp\u00e9ratures moyennes (en \u00b0C) th\u00e9oriques et observ\u00e9es en fonction des latitudes.<\/p>\n\n\n\n\n\n\n
\n

Latitude<\/span><\/p>\n<\/td>\n

\n

0\u00b0<\/span><\/p>\n<\/td>\n

\n

10\u00b0 <\/span><\/p>\n<\/td>\n

\n

20\u00b0<\/span><\/p>\n<\/td>\n

\n

30\u00b0<\/span><\/p>\n<\/td>\n

\n

40\u00b0<\/span><\/p>\n<\/td>\n

\n

50\u00b0<\/span><\/p>\n<\/td>\n

\n

60\u00b0<\/span><\/p>\n<\/td>\n

\n

70\u00b0<\/span><\/p>\n<\/td>\n

\n

80\u00b0<\/span><\/p>\n<\/td>\n<\/tr>\n

\n

Temp\u00e9ratures th\u00e9oriques<\/span><\/p>\n<\/td>\n

\n

32,8<\/span><\/p>\n<\/td>\n

\n

31,7<\/span><\/p>\n<\/td>\n

\n

28,8<\/span><\/p>\n<\/td>\n

\n

22,2<\/span><\/p>\n<\/td>\n

\n

13,9<\/span><\/p>\n<\/td>\n

\n

2,8<\/span><\/p>\n<\/td>\n

\n

-11,1<\/span><\/p>\n<\/td>\n

\n

-23,9<\/span><\/p>\n<\/td>\n

\n

-32,2<\/span><\/p>\n<\/td>\n<\/tr>\n

\n

Temp\u00e9ratures observ\u00e9es HN<\/span><\/p>\n<\/td>\n

\n

26,1<\/span><\/p>\n<\/td>\n

\n

26,7<\/span><\/p>\n<\/td>\n

\n

25,6<\/span><\/p>\n<\/td>\n

\n

20,6<\/span><\/p>\n<\/td>\n

\n

13,9<\/span><\/p>\n<\/td>\n

\n

5,6<\/span><\/p>\n<\/td>\n

\n

-1,1<\/span><\/p>\n<\/td>\n

\n

-10,0<\/span><\/p>\n<\/td>\n

\n

-16,7<\/span><\/p>\n<\/td>\n<\/tr>\n

\n

Temp\u00e9ratures observ\u00e9es HS<\/span><\/p>\n<\/td>\n

\n

26,1<\/span><\/p>\n<\/td>\n

\n

25,6<\/span><\/p>\n<\/td>\n

\n

22,8<\/span><\/p>\n<\/td>\n

\n

18,3<\/span><\/p>\n<\/td>\n

\n

12,2<\/span><\/p>\n<\/td>\n

\n

5,6<\/span><\/p>\n<\/td>\n

\n

-2,2<\/span><\/p>\n<\/td>\n

\n

-11,7<\/span><\/p>\n<\/td>\n

\n

-20,0<\/span><\/p>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

(Valeurs dues \u00e0 Milankovich et cit\u00e9es par H. Landsberg dans Handbook of meteorology <\/em>Bollay et Beers, New York, 1945) HN = h\u00e9misph\u00e8re nord, HS = h\u00e9misph\u00e8re sud<\/span><\/p>\n

 <\/p>\n

Une autre cons\u00e9quence de la pr\u00e9sence des trois cellules est la pr\u00e9sence d\u2019anticyclones permanents aux latitudes 30\u00b0 et de d\u00e9pressions polaires aux environs des latitude 50\u00b0.<\/p>\n

Aux environs des latitudes 30\u00b0, on a la descente d\u2019air suite \u00e0 la rencontre des masses d\u2019air venant de l\u2019\u00e9quateur et de celles venant de latitudes 50\u00b0 (voir figure 43). La descente de cet air froid en altitude vers le sol est ce qu\u2019on appelle une subsidence. L\u2019air froid en se rapprochant du sol se r\u00e9chauffe et s\u2019ass\u00e8che comme cela a \u00e9t\u00e9 expliqu\u00e9 dans le chapitre concernant la pression de vapeur saturante<\/a>. Cet ass\u00e8chement est \u00e0 l\u2019origine de la pr\u00e9sence des grands d\u00e9serts \u00e0 ces latitude. Le plus connu est celui des A\u00e7ores et celui du Sahara qui est \u00e0 l\u2019origine du d\u00e9sert du m\u00eame nom. Nous connaissons moins les anticyclones de l\u2019Ile de P\u00e2ques ou celui d\u2019Hawa\u00ef. On connait la vall\u00e9e de la mort en Californie qui est li\u00e9 \u00e0 l\u2019anticyclone de l\u2019Am\u00e9rique du Nord. En Am\u00e9rique du Sud, C\u2019est le d\u00e9sert d\u2019Atacama (voir figure 44) qui est caus\u00e9 par l\u2019anticyclone de l\u2019Ile de P\u00e2ques. C\u2019est un d\u00e9sert qualifi\u00e9 d\u2019hyperaride.<\/p>\n

\"atacama.png\"<\/a><\/p>\n

Figure 44 : Paysage du d\u00e9sert de l’Atacama au Chili<\/p>\n

Nous reviendrons sur les d\u00e9pressions polaires dans le prochain billet.<\/p>\n","protected":false},"excerpt":{"rendered":"

La circulation g\u00e9n\u00e9rale (2)<\/p>\n","protected":false},"author":3,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[3],"tags":[],"class_list":["post-461","post","type-post","status-publish","format-standard","hentry","category-meteo"],"_links":{"self":[{"href":"http:\/\/vandiepenbeeck.org\/index.php?rest_route=\/wp\/v2\/posts\/461"}],"collection":[{"href":"http:\/\/vandiepenbeeck.org\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/vandiepenbeeck.org\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/vandiepenbeeck.org\/index.php?rest_route=\/wp\/v2\/users\/3"}],"replies":[{"embeddable":true,"href":"http:\/\/vandiepenbeeck.org\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=461"}],"version-history":[{"count":0,"href":"http:\/\/vandiepenbeeck.org\/index.php?rest_route=\/wp\/v2\/posts\/461\/revisions"}],"wp:attachment":[{"href":"http:\/\/vandiepenbeeck.org\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=461"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/vandiepenbeeck.org\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=461"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/vandiepenbeeck.org\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=461"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}