分类必应美图下的文章

约书亚树，加利福尼亚州约书亚树国家公园 Joshua trees in Joshua Tree National Park, California (© Tim Fitzharris/Minden Pictures)

沙漠中的匕首？ Desert daggers?

Joshua Tree National Park

These immensely photogenic and relatable trees, their shaggy, sinewy limbs thrust upward into the pale light of the desert sky, are the main reason people come here to California's Joshua Tree National Park. Joshua Tree was declared a national monument on August 10, 1936, before being designated a national park in 1994. Perhaps no other national park is so completely defined by a single feature, be it a plant or wildlife or natural formation. While Joshua Tree National Park contains other wonders, this tree that looks drawn by Dr. Seuss is what visitors come to celebrate.

The park (and the town of the same name) could also be called the hippest national park in the country, owing to its proximity to Los Angeles, and the Insta-worthy, charismatic flora that have helped make JT a darling on social media. Van lifers, artists, celebrities, and other creative bohemians have fueled a boom in tourism, not just to the park itself, but to the surrounding towns, like Pioneertown. The kitschy outpost served as an old Hollywood set and is now a center of nightlife in the area. Pappy & Harriet's Pioneertown Palace serves artisanal cocktails with its barbecue and features live music, sometimes from the likes of Paul McCartney, Robert Plant, and Patti Smith. And if you can't find an elderflower martini in Joshua Tree, then Palm Springs and Indio and Coachella are a short drive away, something Yellowstone and Yosemite can't claim.

But for those going purely for the nature—the hikers, rock climbers, campers, and stargazers—the 1,200-square-mile park is no less a marvel. Two deserts, the high-elevation Mojave and the low-elevation Colorado, merge here, each with its own ecosystem. The Joshua tree itself grows only on the Mojave side, at elevations between 1,300 and 5,900 feet. Most of the world's Joshua trees are found here. A variety of yucca, Joshua trees live to be 500 and 1,000 years old with roots as deep as 35 feet. Most believe their name was first concocted by Mormon pioneers who likened their branches to the oustretched arms of the biblical Joshua. It proved catchier than its botanical name, Yucca brevifolia. And as any influencer worth their followers will tell you, it makes for a much more memorable hashtag.

约书亚树国家公园

这些非常上镜且相互关联的树木，它们粗壮有力的四肢伸向沙漠天空的暗淡光线，是人们来到加利福尼亚州约书亚树国家公园的主要原因。约书亚树于1936年8月10日被宣布为国家纪念碑，然后于1994年被指定为国家公园。也许没有其他国家公园如此完全由单一特征来定义，无论是植物、野生动物还是自然形成物。约书亚树国家公园还有其他的奇观，这棵树看起来是苏斯博士画的，是游客们来庆祝的。

这个公园（和同名的小镇）也可以被称为美国最时髦的国家公园，因为它靠近洛杉矶，以及有魅力的植物群，使JT成为社交媒体上的宠儿。范利弗、艺术家、名人和其他富有创意的波西米亚人推动了旅游业的繁荣，不仅是公园本身，还有周边城镇，如先锋镇。这个俗气的前哨站曾经是好莱坞的老片场，现在是该地区的夜生活中心。Pappy&Harriet的先锋城宫殿提供手工鸡尾酒和烧烤，并配有现场音乐，有时来自保罗·麦卡特尼（Paul McCartney）、罗伯特·普兰特（Robert Plant）和帕蒂·史密斯（Patti Smith）。如果你在约书亚树上找不到接骨木花马提尼酒，那幺棕榈泉、Indio和Coachella就在很短的车程之外，这是黄石公园和约塞米蒂不能宣称的。

但对于那些纯粹为了大自然而去的徒步旅行者、攀岩者、露营者和观星者来说，1200平方英里的公园同样是一个奇迹。两个沙漠，高海拔的莫哈韦和低海拔的科罗拉多，在这里汇合，每个沙漠都有自己的生态系统。约书亚树本身只生长在莫哈韦一侧，海拔在1300到5900英尺之间。世界上大多数约书亚树都在这里找到。各种各样的丝兰树、约书亚树的树龄分别为500年和1000年，树根深达35英尺。大多数人相信他们的名字是摩门教先驱们首先炮制出来的，他们把他们的树枝比作圣经中约书亚被驱逐的手臂。事实证明，它比其植物学名称短叶丝兰更吸引人。任何有影响力的追随者都会告诉你，这是一个更令人难忘的标签。

阿根廷圣克鲁斯的洛斯马诺斯洞穴 Cueva de las Manos (Cave of the Hands) in Santa Cruz, Argentina (© Adwo/Alamy)

9000年前的手印 9,000-year-old handprints

International Day of the World's Indigenous Peoples

What at first glance appears to be graffiti tagged on a rock wall is, in fact, artwork created by the first human settlers of this remote region deep in Argentine Patagonia. It's thought that the cave paintings were made between 13,000 and 9,500 years ago. The archaeological site is known in Spanish as the Cueva de las Manos (Cave of the Hands). It's the largest display of prehistoric handprints in the world, made all those years ago by people holding a hand against the rock wall and blowing pigments through tubes made of bone. Of the 829 black, white, red, and ochre prints, most are of young male hands. One print has six fingers, and only 31 are of right hands.

The cave paintings were created in at least three waves over thousands of years by ancestors of the Tehuelche people. Archaeologists have hypothesized that the artists were hunter-gatherers. This theory is supported by the fact that even older than the handprints are depictions of guanacos (a relative of the llama, and the main source of food at the time); rheas (large flightless birds); and hunting scenes.

Today, more than 370 million Indigenous people live in various regions of the world, like the Teheulche, who continue to live in Patagonia near the southern border between Argentina and Chile. To honor and protect the rights of the world's current Indigenous populations, the UN marks each August 7 as International Day of the World's Indigenous Peoples. We'll raise our hands in support of that.

世界土著人民国际日

乍一看，岩壁上的涂鸦标记实际上是阿根廷巴塔哥尼亚这个偏远地区的第一批人类定居者创作的艺术品。据认为，这些洞穴壁画是在13000年至9500年前绘制的。该考古遗址在西班牙语中被称为Cueva de las Manos（手洞）。这是世界上最大规模的史前手印展示会，多年前，人们用手抵着岩壁，用骨头制成的管子吹颜料。在829张黑、白、红和赭色的照片中，大多数是年轻男性的手。一个指纹有六个手指，只有31个是右手的。

这些洞穴壁画是特韦尔奇人的祖先在数千年中至少三次创作的。考古学家假设这些艺术家是狩猎采集者。这一理论得到了以下事实的支持：比手印更古老的是美洲驼（美洲驼的亲戚，当时的主要食物来源）的描述；大型不会飞的鸟类；还有狩猎场面。

今天，有3.7亿多土著人生活在世界各地，如特霍尔切人，他们继续生活在阿根廷和智利南部边界附近的巴塔哥尼亚。为了尊重和保护当今世界土著居民的权利，联合国每年8月7日都将其定为世界土著人民国际日。我们将举手表示支持。

圣埃尔姆附近的潘塔留岛鸟瞰图，西班牙马略卡岛 Aerial view of the island Pantaleu near Sant Elm, Mallorca, Spain (© Dimitri Weber/Azing航空公司)

汪洋中的小岛 Little Island, Big Sea

Pantaleu

There isn't much to the tiny island of El Pantaleu (or Es Pantaleu in Catalan), cast off the westernmost shore of Mallorca, itself a relatively small island only 30-40 miles across. Pantaleu and Mallorca are part of the archipelago of Balearic Islands in the Balearic Sea, off the east coast of Spain. Mallorca, Ibiza, Menorca, and Formentera are the chain's four major islands and are famous as tourist destinations popular among those seeking the warm Mediterranean climate and inviting shoreline.

Pantaleu is more precisely an islet, a mere rock of about six acres in size. Its highest point is 80 feet. Not much grows on El Pantaleu, and no one lives on it. Mallorca is only about 1,000 feet away, making it a vigorous but doable swim for the many who have tried from the beach at the village of Sant Elm. Technically, no one is allowed to step foot onto Pantaleu, because it is designated a nature reserve along with the much larger Dragonera Island a few miles farther to the west.

Pantaleu is most useful as a wind break for boats, as you can see from this aerial photo. The notch between the islet and the main island is a popular anchorage for the many pleasure boats that cruise these waters. Even centuries ago, sailors understood the value of Pantaleu as an anchorage. In 1229, young James I the Conqueror, King of Aragon, and his fleet sought refuge from a storm behind Pantaleu before he embarked on his campaign to invade the Balearic Islands and start making good on his nickname. These days, most of the turf battles around here have been settled, although you might have to parry a vacationer for a spot on the sand or a table at happy hour.

潘塔留

位于马略卡岛最西岸的小岛El Pantaleu（或加泰罗尼亚的Es Pantaleau）没有什么特别之处，它本身是一个直径只有30-40英里的相对较小的岛屿。Pantaleu和Mallorca是西班牙东海岸巴利阿里海巴利阿里群岛的一部分。马洛卡岛、伊维萨岛、梅诺卡岛和福门特拉岛是该群岛的四个主要岛屿，是著名的旅游目的地，深受寻求温暖地中海气候和迷人海岸线的游客的欢迎。

潘塔留更准确地说是一个小岛，一块只有六英亩大小的岩石。它的最高点是80英尺。El Pantaleu岛上没有多少植物，也没有人靠它生活。马略卡岛离这里只有1000英尺远，对于许多在圣埃尔姆村海滩上尝试游泳的人来说，这是一次充满活力但可行的游泳。从技术上讲，任何人都不允许踏上潘塔留岛，因为它被指定为自然保护区，与西边几英里远的大得多的龙时代岛一起。

从这张航拍照片中可以看出，Pantaleu是船只避风的最佳场所。小岛和主岛之间的缺口是许多游船在这些水域航行的热门锚地。甚至在几个世纪前，水手们就知道潘塔留作为锚地的价值。1229年，年轻的征服者、阿拉贡国王詹姆斯一世和他的舰队在开始入侵巴利阿里群岛并开始利用他的绰号之前，在潘塔留后面躲避风暴。这些天来，这里的大部分地盘之争都已经解决了，尽管你可能不得不避开度假者在沙滩上或欢乐时光的餐桌上。

杭州西湖的古典中国园林 Classical Chinese Garden at west lake in Hangzhou in fall (© DANNY HU/Getty Images)

贴秋膘了吗？ Fleshing out in autumn

The beginning of autumn

The beginning of autumn is the 13th solar term in the twenty-four solar terms and the first solar term in autumn; in nature, everything begins to grow from lush and mature to bleak and mature. The beginning of autumn does not mean the end of the hot weather. The beginning of autumn is still in the hot period, the summer has not yet come out, and the weather is still very hot during the early autumn. The so-called "hot in the three volts", there is also the saying "one volt after the autumn", there will be at least "one volt" of extremely hot weather after the beginning of autumn.

From the perspective of meteorological changes, entering autumn means that rainfall and humidity are at a turning point in the year and tend to decline or decrease. With the change of seasons, the rainfall and dry humidity in the South have obvious changes; In northern China, the obvious change is the temperature.

初秋

秋初是二十四节气中的第十三节气，也是秋季的第一节气；在自然界中，一切都开始从繁茂和成熟到暗淡和成熟。秋天的开始并不意味着炎热天气的结束。初秋仍然处于炎热时期，夏天还没有出来，初秋的天气仍然很热。所谓“热在三伏”，也有“秋后一伏”之说，初秋后至少会有“一伏”的酷热天气。

从气象变化的角度来看，进入秋季意味着一年中降雨量和湿度处于转折点，并趋于下降或减少。随着季节的变化，南方的降雨量和干湿度有明显的变化；在中国北方，最明显的变化是气温。

旧金山湾的盐滩 Salt flats in San Francisco Bay (© Jeffrey Lewis/Tandem Stills + Motion)

一个咸咸的地点 A salty situation

San Francisco Bay salt flat

You might be wondering where the volcano is in today's photo, but that's not lava. These are salt evaporation ponds in San Francisco Bay. If you happen to be in the air and flying over this part of the country, you'll notice not just the bright orange but various greens and blues and even magenta pools that are part of the famous salt ponds. The vibrant colors are determined by brine shrimp, algae, and other microorganisms and their responses to different levels of salt. This orange results from about a mid-level saline concentration and the presence of tiny brine shrimp in the water. Green indicates low levels of salt, while pink or red are signs of high salt content in an algae-rich pond.

When Spanish explorers and missionaries arrived in the area in the late 18th century, members of the Indigenous Ohlone people were already extracting salt from the naturally occurring ponds. The California Gold Rush (1848–1855) brought waves of settlers to the region, and salt became one of San Francisco's largest industries. Roughly 80% of the wetland was eventually lost to salt mining, landfill, or other industrial alteration. But since 2003, many of these tidal flats have been acquired by federal and state agencies as well as private foundations to be restored to their original state. The restoration process will take decades, but even as the wetlands are being restored, about half a million tons of sea salt are harvested from the ponds every year.

旧金山湾盐滩

你可能想知道今天照片中的火山在哪里，但那不是熔岩。这些是旧金山湾的盐蒸发池。如果你碰巧在空中飞过这个国家的这一地区，你不仅会注意到明亮的橙色，还会注意到各种绿色和蓝色，甚至是品红池，它们是著名盐池的一部分。鲜艳的颜色是由盐水虾、藻类和其他微生物及其对不同盐含量的反应决定的。这种橙色是由于大约中等浓度的盐水和水中存在微小的盐水虾造成的。绿色表示含盐量低，而粉色或红色表示富藻池塘的含盐量高。

18世纪末，当西班牙探险家和传教士抵达该地区时，当地的奥隆人已经在从天然池塘中提取盐。加利福尼亚淘金热（1848-1855）为该地区带来了一波又一波的定居者，盐业成为旧金山最大的产业之一。大约80%的湿地最终因盐矿开采、填埋或其他工业改造而消失。但自2003年以来，联邦和州政府机构以及私人基金会收购了许多这些潮滩，以恢复其原始状态。恢复过程将需要几十年，但即使湿地正在恢复，每年从池塘中收获约50万吨海盐。

夜晚的爱丁堡城市天际线，苏格兰 Edinburgh city skyline at night, Scotland (© Suranga Weeratuna/Alamy)

节日热潮 Festival fever

Edinburgh festivals

Here's the world-famous Edinburgh Castle, lit up in all its glory as it keeps watch over Scotland's capital city. Today the castle hosts the Royal Edinburgh Military Tattoo, a full-on Scottish experience, with bagpipes, drums, and seemingly enough kilts to cover all of Scotland. Enthusiastic visitors can also indulge in whisky and haggis in one of the many hostelries on the Royal Mile, the colorful, bustling historic street that wends its way from the castle down to the Palace of Holyroodhouse, Queen Elizabeth II's official residence in Scotland.

The Tattoo is a spectacular show of military music, dancing, and ceremony that runs alongside the Edinburgh International Festival, which starts today and goes through August 27, and the Edinburgh Festival Fringe (Aug. 5-29), its sprawling, less formal sidekick. The main festival—celebrating its 75th anniversary in 2022—is an invitation-only event that brings together top classical musicians and stage performers from around the globe. The Fringe is decidedly casual. It's the world's largest arts festival and features all types of music, street performers, amateur theater productions, stand-up comedy, and more, often in city streets, church halls, pubs...basically any available space. Think free-spirited and fun. One thing's certain: Edinburgh in August keeps everyone entertained.

爱丁堡音乐节

这是举世闻名的爱丁堡城堡，它在守卫苏格兰首都的同时，灯火通明。今天，城堡里有皇家爱丁堡军事纹身，这是一次充满苏格兰风情的经历，风笛、鼓和方格呢短裙似乎足以覆盖整个苏格兰。热情的游客还可以在皇家大道（Royal Mile）上的众多招待所之一尽情享受威士忌和哈吉斯酒。皇家大道是一条色彩斑斓、熙熙攘攘的历史街区，从城堡一直延伸到伊丽莎白女王二世在苏格兰的官邸霍利罗德豪斯宫（Palace of Holyroodhouse）。

纹身是一场壮观的军事音乐、舞蹈和仪式表演，与爱丁堡国际艺术节（从今天开始，一直持续到8月27日）和爱丁堡边缘艺术节（8月5日至29日）同时举行。爱丁堡艺术节是其规模庞大、不太正式的伙伴。2022年庆祝其75周年的主要节日是一个邀请活动，汇集了来自世界各地的顶级古典音乐家和舞台表演者。流苏绝对是随意的。这是世界上最大的艺术节，以各种类型的音乐、街头艺人、业余戏剧制作、单口喜剧等为特色，通常在城市街道、教堂大厅、酒吧……基本上是任何可用空间。想一想自由和乐趣。有一件事是肯定的：八月的爱丁堡让每个人都很开心。

上海浦东森林心形洞穴鸟瞰图，中国 Aerial view of heart shaped cave in the forest, Pudong, Shanghai, China (© Yaorusheng/Getty Images)

最浪漫的中国传统节日 The most romantic traditional festival

QiXi Festival

Derived from the worship of stars, the Tanabata Festival is the birthday of the seventh sister in the traditional sense. The seventh sister (VEGA) is a weaver of clouds and the textile industry, and the patron saint of lovers, women, and children. The Tanabata Festival is not only a festival to worship the seventh sister, but also a festival of love. It is a comprehensive festival with women as the main body, with the folk legend of "Cowherd and Weaver Girl" as the carrier, with praying, begging, and love as the theme.

With the development of history, QiXi has been endowed with the beautiful love legend of "Cowherd and Weaver Girl". Because it is endowed with the connotation related to love, it has become a festival symbolizing love, which is considered to be a very romantic traditional festival in China and has produced the cultural meaning of "Chinese Valentine's Day" in contemporary times.

七夕节

七夕节源于对星星的崇拜，在传统意义上是七姐的生日。七姐妹（织女星）是云和纺织业的编织者，是情人、妇女和儿童的守护神。七夕节不仅是祭拜七姐的节日，也是爱的节日。这是一个以妇女为主体，以民间传说“牛郎织女”为载体，以祈祷、乞讨、爱情为主题的综合性节日。

随着历史的发展，七夕被赋予了“牛郎织女”的美丽爱情传说。由于它被赋予了与爱相关的内涵，它已成为象征爱的节日，在中国被认为是一个非常浪漫的传统节日，并在当代产生了“中国情人节”的文化意义。

走上这条人迹常见的小径 Take the trail more traveled by

Happy Birthday Capitol Reef National Park

You won't find a lot of solitude on the Hickman Bridge Trail, a 1.7-mile route in Capitol Reef National Park that leads to this magnificent natural arch. The trail is used by hikers, runners, and nature lovers drawn by incredible rock formations, gullies, and remnants from the Fremont Culture Native American civilization from the early part of the 20th century. Hickman Bridge itself is one of the best-known geologic features of the park.

Capitol Reef National Park was first established as a national monument on this day in 1937, then became a national park in 1971. Capitol Reef is named for its massive rock domes that reminded nearby residents of that famous rotunda of the US Capitol Building back in Washington, DC. Why Capitol 'Reef,' though? Because the imposing formations were major obstacles to travelers through the region, the same way a coral reef is an obstacle to sailors.

The geology of the park is defined by the nearly 100-mile Waterpocket Fold, a wrinkle in the Earth's crust that formed around the end of the dinosaur era. Wind, rain, and time have eroded the Navajo Sandstone into colorful canyons, buttes, and natural arches like Hickman Bridge. The dramatic rock formations make Capitol Reef a favorite destination in the American West.

生日快乐国会山 珊瑚礁国家公园

在希克曼大桥小径上你不会发现太多的孤独，这条小径位于国会山礁国家公园，全长1.7英里，通往这座宏伟的天然拱门。这条小径供远足者、跑步者和自然爱好者使用，它们由难以置信的岩层、沟壑和20世纪早期弗里蒙特文化-美洲原住民文明的遗迹绘制而成。希克曼大桥本身就是公园最著名的地质特征之一。

国会山礁国家公园于1937年的今天首次作为国家纪念碑建立，然后在1971年成为国家公园。国会山礁以其巨大的岩石圆顶而命名，这让附近的居民想起了位于华盛顿特区的美国国会大厦的著名圆形大厅。然而，为什么国会大厦是“暗礁”？因为壮观的地形是该地区旅行者的主要障碍，就像珊瑚礁是水手的障碍一样。

公园的地质特征是近100英里的水袋褶皱，这是在恐龙时代末期形成的地壳褶皱。风、雨和时间把纳瓦霍砂岩侵蚀成了五颜六色的峡谷、山丘和希克曼大桥那样的天然拱门。引人注目的岩层使国会山礁成为美国西部最受欢迎的目的地。

漏出“天窗”的熔岩管，夏威夷火山国家公园 Skylight into an active lava tube, Hawaii Volcanoes National Park, Hawaii (© Tom Schwabel/Tandem Stills + Motion)

世界上最活跃的火山 The most active volcano in the world

Hawai'i Volcanoes National Park at 106

The orange glow of a lava tube like the one pictured here is a frequent site on Hawaii's Kilauea, the youngest volcano on one of the youngest islands on Earth. In near constant eruption for the last 40 years, Kilauea is widely considered the most active volcano in the world and is the main attraction at Hawaii Volcanoes National Park, which was created on this day in 1916. The park, which was designated an International Biosphere Reserve and a World Heritage Site, also includes another active volcano, Mauna Loa, the world's most massive shield volcano—Mauna Loa last erupted in 1984. Together, they are among the most studied volcanoes in the world.

The volcanoes of the Big Island of Hawaii offer a real-time glimpse into the ongoing creation of the entire Hawaiian island chain, a process that has been underway for tens of millions of years. Hawaii as we know it owes its existence to a volcanic hotspot on the seafloor. Magma seeps from this hotspot and turns into solid rock. Once enough magma is extruded, the rock breaks the surface of the sea and becomes an island. The island continues to grow until the Pacific tectonic plate moves the island off the hotspot. The hotspot remains stationary, constantly creating new islands. In fact, the next Hawaiian island, named Loihi, is about 20 miles from Hawaii and 3,000 feet below the surface of the ocean. In less than 100,000 years, it is expected to replace the Big Island as the youngest island in the chain, and it too will have its turn at hosting visitors who buy timeshare condos.

Hawaiian religion credits the creation of Hawaii to Pele, the goddess of fire and volcanoes. Possessing a fiery temper and a passionate nature, she is said to make her home in the Halema'uma'u caldera here on Kilauea. From her volcano home she controls the flow of lava and frequency of eruptions. According to modern legend, she sometimes wanders near the park as an old woman wearing a red muumuu, with a white dog, as a warning that a new eruption is soon to come.

106号夏威夷火山国家公园

图中所示的橙色熔岩管辉光是夏威夷基拉韦厄岛上的一个常见地点，基拉韦耶岛是地球上最年轻岛屿之一上最年轻的火山。在过去40年中，基拉韦厄火山几乎持续喷发，被广泛认为是世界上最活跃的火山，是1916年创建的夏威夷火山国家公园的主要景点。该公园被指定为国际生物圈保护区和世界遗产，还包括另一座活火山，莫纳罗亚，世界上最大的盾状火山莫纳洛上次喷发是在1984年。加在一起，它们是世界上研究最多的火山之一。

夏威夷大岛上的火山可以实时观察整个夏威夷岛链的形成过程，这一过程已经持续了数千万年。众所周知，夏威夷的存在得益于海底的火山热点。岩浆从这个热点渗出，变成固体岩石。一旦足够的岩浆被挤出，岩石就会冲破海面，变成一个岛屿。该岛继续增长，直到太平洋构造板块将该岛移出热点。热点保持静止，不断形成新的岛屿。事实上，下一个夏威夷岛，名为Loihi，距离夏威夷约20英里，海拔3000英尺。预计在不到10万年的时间里，它将取代大岛，成为这一链条中最年轻的岛屿，轮到它接待购买分时度假公寓的游客。

夏威夷宗教将夏威夷的诞生归功于火与火山女神贝利。她脾气暴躁，生性热情，据说住在基拉韦厄岛的Halema'uma'u火山口。她在火山口的家中控制着熔岩的流动和喷发的频率。根据现代传说，她有时会在公园附近漫步，就像一个穿着红色muumuu的老妇人，带着一只白色的狗，作为新火山爆发即将到来的警告。

“夜光”云 ‘Night shining' clouds

Noctilucent clouds

It's around this time of year when some lucky people get to witness these rare, wonderous clouds. Known as noctilucent, or ‘night shining,' clouds, they're the highest clouds in our sky and are only visible during summer. They're made up of icy dust glowing at the edge of space, roughly 50 miles above the planet's surface. The trick to seeing them is to gaze up into the sky at twilight, when the sun has already set on the Earth's surface, but the high-altitude noctilucent cloud is still in sunlight. These clouds occur almost exclusively at high latitudes, roughly between about 50° and 70° North or South.

Generally colorless or light blue, noctilucent clouds are distinct in their patterns of streaks, waves, and whirls. It's not fully known why they happen, though some recent studies suggest methane levels could contribute to atmospheric water vapor that rises high into the mesosphere where they form. What is known is that they were first observed in 1885, making them the newest cloud type.

夜光云

大约在每年的这个时候，一些幸运的人看到了这些罕见的、奇妙的云。夜光云是我们天空中最高的云，只有在夏天才能看到。它们是由在太空边缘发光的冰尘组成的，距离地球表面大约50英里。看到它们的诀窍是在黄昏时抬头仰望天空，这时太阳已经落在地球表面，但高海拔的夜光云仍在阳光下。这些云几乎只出现在高纬度地区，大约在南北50°到70°之间。

通常无色或淡蓝色，夜光云的条纹、波浪和漩涡图案不同。虽然最近的一些研究表明，甲烷含量可能会导致大气中的水蒸气上升到它们形成的中间层，但目前还不完全清楚它们为什么会发生。已知的是，1885年首次观察到甲烷含量，使其成为最新的云类型。

星空迷