{"id":1076,"date":"2010-02-09T09:35:10","date_gmt":"2010-02-09T12:35:10","guid":{"rendered":"http:\/\/scienceblogs.com.br\/cienciaaonatural\/2010\/02\/agua_que_queima\/"},"modified":"2010-02-09T09:35:10","modified_gmt":"2010-02-09T12:35:10","slug":"agua_que_queima","status":"publish","type":"post","link":"https:\/\/www.blogs.unicamp.br\/cienciaaonatural\/2010\/02\/09\/agua_que_queima\/","title":{"rendered":"\u00c1gua Que Queima"},"content":{"rendered":"

\"ciencia_ao_natural_1000<\/a>A natureza de algo nunca \u00e9 parece o que ser.
\n\u00c9 mais. Ou menos. Mas exactamente aquilo que parece ser, \u00e9 raro.
\nUma gota de \u00e1gua. Cristalina. Fresca.
\nAinda assim, e apoiando o senso comum de um qualquer agricultor ou mero jardineiro de fim-de-semana, o refrescante efeito da rega durante as horas de maior calor pode n\u00e3o ser o desejado.
\nMais.
\nAs gotas de \u00e1gua que caem sobre a folhagem poder\u00e3o provocar queimaduras nos tecidos vegetais.
\nCada gota ir\u00e1 funcionar como uma lente ampliando o efeito energ\u00e9tico sobre as folhas da vegeta\u00e7\u00e3o conduzindo assim ao efeito contr\u00e1rio do que se pretenderia.
\nRefer\u00eancia:<\/strong>
\n\u00c1d\u00e1m Egri, \u00c1kos Horv\u00e1th, Gy\u00f6rgy Kriska and G\u00e1bor Horv\u00e1th. Optics of sunlit water drops on leaves: conditions under which sunburn is possible. New Phytologist. (2009) doi: 10.1111\/j.1469-8137.2009.03150.x<\/a>
\n\"12.jpg\"<\/a>
\nAbstract<\/strong>
\n“It is a widespread belief that plants must not be watered in the midday sunshine, because water drops adhering to leaves can cause leaf burn as a result of the intense focused sunlight. The problem of light focusing by water drops on plants has never been thoroughly investigated.
\nHere, we conducted both computational and experimental studies of this phyto-optical phenomenon in order to clarify the specific environmental conditions under which sunlit water drops can cause leaf burn.
\nWe found that a spheroid drop at solar elevation angle \u03b8 \u2248 23\u00b0, corresponding to early morning or late afternoon, produces a maximum intensity of focused sunlight on the leaf outside the drop’s imprint. Our experiments demonstrated that sunlit glass spheres placed on horizontal smooth Acer platanoides (maple) leaves can cause serious leaf burn on sunny summer days.
\nBy contrast, sunlit water drops, ranging from spheroid to flat lens-shaped, on horizontal hairless leaves of Ginkgo biloba and Acer platanoides did not cause burn damage. However, we showed that highly refractive spheroid water drops held ‘in focus’ by hydrophobic wax hairs on leaves of Salvinia natans (floating fern) can indeed cause sunburn because of the extremely high light intensity in the focal regions, and the loss of water cooling as a result of the lack of intimate contact between drops and the leaf tissue.”
\nImagens:<\/strong>
\nLu\u00eds Azevedo Rodrigues
\n(com Nokia N73)
\ne do artigo<\/p>\n","protected":false},"excerpt":{"rendered":"

A natureza de algo nunca \u00e9 parece o que ser. \u00c9 mais. Ou menos. Mas exactamente aquilo que parece ser, \u00e9 raro. Uma gota de \u00e1gua. Cristalina. Fresca. Ainda assim, e apoiando o senso comum de um qualquer agricultor ou mero jardineiro de fim-de-semana, o refrescante efeito da rega durante as horas de maior calor […]<\/p>\n","protected":false},"author":470,"featured_media":2275,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_monsterinsights_skip_tracking":false,"pgc_sgb_lightbox_settings":"","_vp_format_video_url":"","_vp_image_focal_point":[],"footnotes":""},"categories":[3,10,13],"tags":[42,314,548,705],"class_list":["post-1076","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-bioderivados","category-descubra-as-diferencas","category-duvidas-existenciais","tag-agua","tag-fotos","tag-plants","tag-water"],"jetpack_featured_media_url":"https:\/\/www.blogs.unicamp.br\/cienciaaonatural\/wp-content\/uploads\/sites\/230\/2010\/02\/ciencia_ao_natural_1000-copy.jpg","_links":{"self":[{"href":"https:\/\/www.blogs.unicamp.br\/cienciaaonatural\/wp-json\/wp\/v2\/posts\/1076","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.blogs.unicamp.br\/cienciaaonatural\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.blogs.unicamp.br\/cienciaaonatural\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.blogs.unicamp.br\/cienciaaonatural\/wp-json\/wp\/v2\/users\/470"}],"replies":[{"embeddable":true,"href":"https:\/\/www.blogs.unicamp.br\/cienciaaonatural\/wp-json\/wp\/v2\/comments?post=1076"}],"version-history":[{"count":0,"href":"https:\/\/www.blogs.unicamp.br\/cienciaaonatural\/wp-json\/wp\/v2\/posts\/1076\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.blogs.unicamp.br\/cienciaaonatural\/wp-json\/wp\/v2\/media\/2275"}],"wp:attachment":[{"href":"https:\/\/www.blogs.unicamp.br\/cienciaaonatural\/wp-json\/wp\/v2\/media?parent=1076"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.blogs.unicamp.br\/cienciaaonatural\/wp-json\/wp\/v2\/categories?post=1076"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.blogs.unicamp.br\/cienciaaonatural\/wp-json\/wp\/v2\/tags?post=1076"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}