第1部分：https://blog.sciencenet.cn/home.php?mod=space&uid=306792&do=blog&id=1355804

第2部分：https://blog.sciencenet.cn/home.php?mod=space&uid=306792&do=blog&id=1355915

第3部分：https://blog.sciencenet.cn/home.php?mod=space&uid=306792&do=blog&id=1355980

Every summer, a high-pressure system, the North Pacific High, parks itself off the California coast, altering wind patterns and churning up the cold-water California Current that hugs the coast. The rest is all saturation points and dew points: Water vapor rises from the sea, turning into droplets that cling to microscopic airborne particles, like sea-salt aerosols, to form clouds. But these clouds stay low to the ocean, held there by a temperature inversion that creates a “marine layer.”

每年夏天，北太平洋高压系统都会出现在加州海岸外，改变风向，并造成沿着海岸的冷的加利福尼亚洋流。其余的取决于饱和点和露点：水蒸气从海中升起，变成水滴，附着在空气中的微小颗粒上，如海盐气溶胶，形成云。但是这些云层悬浮在离海面不远的大气中，因为那里有一个所谓的“大气海洋层”，它是“垂直气温反转”造成的。

Sometimes this marine layer is low enough to be considered fog.

有时这个大气海洋层低到足以被认为是海雾。

“Fog is so complex,” said Alicia Torregrosa, an environmental scientist with the U.S. Geological Survey who has done deep studies on California’s coastal fog. “And the complexity has to do with thermal relationships.”

“雾是如此复杂，”美国地质调查局的环境科学家艾丽西亚·托雷格罗萨（Alicia Torregrosa）说，她对加州海雾进行了深入研究。 “而复杂性牵涉到大气热力关系。”

The start, really, is the North Pacific High. Dr. Weiss calls it “the birth of fog.”

加州海雾真正的起因是北太平洋高压。 魏斯（Weiss） 博士称其为“雾的起源”。
 

As the world warms, however, this balance could be at risk, with unpredictable consequences.

然而，随着地球变暖，这种平衡可能会面临风险，带来不可预测的后果。

“What I want to know is, do we expect more or less clouds with climate change,” Dr. Clemesha said. “I still don’t know enough to say confidently. It’s complicated.”

“我想知道的是，随着气候变化，我们预计会有更多或更少的云，”克莱梅沙（Clemesha）博士说。 “以我现有的知识，我仍然无法自信地回答这个问题。因为情况很复杂。”

Otto Klemm, a professor of climatology at the University of Münster in Germany, is more certain. He has studied data from airports all over the world.

德国明斯特大学气候学教授奥托·克莱姆（Otto Klemm）则非常肯定。他研究了来自世界各地机场的数据。

“Fog has decreased, more or less everywhere,” he said, attributing the link both to climate change and to lower levels of air pollution, as water droplets have fewer particulates to cling to. “Of about 1,000 stations, 600 or 700 show a statistically significant decrease. All over Europe, all over North America, South America — everywhere.”

他说：“雾在各地或多或少都在减少，”他将这种联系归因于气候变化和空气污染的改进，因为水滴可以附着的颗粒更少。 “在大约 1,000 个站点中，有 600 或 700 个显示出统计学上有意义的减少。遍布欧洲、北美、南美——无处不在。”

But back to California, and the fog along the coast.

让我们回到加州，继续谈论它沿岸的海雾。

“We know that the planet is warming, we know that oceans are getting warmer,” said Travis O’Brien, an assistant professor of earth and atmospheric sciences at Indiana University who has studied the California coast extensively. “What we don’t know is what’s happening in the really near coastal environment. In particular, ocean temperatures right along the coasts are a big question mark, and they have long been thought to be really important for coastal fog.”

“我们知道地球正在变暖，我们知道海洋正在变暖，”印第安纳大学地球与大气科学助理教授特拉维斯·奥布莱恩（Travis O’Brien）说；他着重研究加州海岸。 “我们不知道在靠近沿海的海洋环境中发生了什么。尤其是沿海的海温是一个很大的未知数，尽管长期以来人们一直认为它对海雾非常重要。”

Research can be contradictory or counterintuitive. A 2017 study using observational records of ships off the California coast suggests that fog is heavier than it used to be. So maybe it’s just not coming onshore the way it once was.

一些研究结果可能会有矛盾或违反直觉。2017 年的一项使用加州海岸附近船只观测记录的研究表明，雾比过去更重。所以也许海雾只是不像以前那样涌入到岸上。

In Southern California, during the periods colloquially called “May Gray” and “June Gloom,” research shows an increase in cloud-base height — low clouds persist, but are now less likely to be in the form of ground-touching fog — because of the urban heat-island effect. Some experts surmise something similar is happening in San Francisco, too.

研究表明，在南加州的俗称“五月灰蒙蒙”和“六月阴霾霾”的时期，云底高度增加——低云持续存在，但现在不太可能以接触地面的雾的形式出现——因为有城市热岛效应。一些专家推测旧金山也正在在发生类似的情况。

And maybe fog has made a comeback. Dr. O’Brien updated data from area airport observations and found that the declining fog levels in the second half of the 20th century have appeared to stabilize. Other researchers, using satellite technology, concluded this month “that the number of foggy days fluctuates considerably year-to-year with no discernible positive or negative trend occurring between 2000 and 2020.”

也许雾已经卷土重来。 奥布莱恩（O'Brien） 博士更新了地区机场观测数据，发现 在20 世纪下半叶减少的雾，似乎已经趋于稳定水平。其他使用卫星资料的研究人员在本月得出结论，“雾的天数逐年波动很大，在 2000 ～ 2020 期间，没有出现明显的正的或负的趋势。”

No one is quite sure why that is.

没有人知道为什么会是这样。

True to form and character, fog varies from day to day, minute to minute, place to place. To say that fog is increasing or decreasing depends on so many variables. Is this valley, this hill, this beach, this city as foggy as it used to be? How can you really tell?

从形式和特征来说，雾每天、每分钟、每时、每刻都在变化。说雾是增加还是减少取决于很多变量。这山谷、山丘、海滩、这座城市，是否还像从前一样雾蒙蒙的？你怎么能真的知道？

There may be no place with a deeper connection to fog than the California coast, especially the 150 miles or so from Monterey to Point Reyes National Seashore, where the lighthouse, shrouded in fog about 200 days a year, is one of the foggiest places on the continent.

可能没有比加州海岸与雾的联系更深的地方了，尤其是从蒙特雷（Monterey）到雷耶斯角（Point Reyes）国家海岸带的 150 英里左右的地方，那里的灯塔每年大约有 200 天被雾笼罩，是美国本土最有雾的地方之一。

Millions live within 50 miles of the coast along that stretch. Daily high temperatures might fall short of 60 degrees near the ocean but be more than 100 degrees inland, all depending on fog’s reach.

数百万人居住在那150 英里附近，在离海岸 50 英里的范围内。海洋附近的每日高温可能低于华氏 60 度，但内陆可能超过 华氏100 度，这一切都取决于海雾的涌入范围。

In between, many feel the effect of fog but rarely see it — a breath of cool afternoon air, maybe, or a bracing chilled wind that upends outdoor plans in the evening.

在这一地带，许多人感受到海雾的影响，但很少看到海雾——人们感觉到的，也许是一股凉爽的午后气流，或是一股令人打颤的冷风，让你不想在晚上出门。

（待续）

摸的旧金

第1部分：https://blog.sciencenet.cn/home.php?mod=space&uid=306792&do=blog&id=1355804

第2部分：

https://blog.sciencenet.cn/home.php?mod=space&uid=306792&do=blog&id=1355915

第3部分：https://blog.sciencenet.cn/home.php?mod=space&uid=306792&do=blog&id=1355980

Every summer, a high-pressure system, the North Pacific High, parks itself off the California coast, altering wind patterns and churning up the cold-water California Current that hugs the coast. The rest is all saturation points and dew points: Water vapor rises from the sea, turning into droplets that cling to microscopic airborne particles, like sea-salt aerosols, to form clouds. But these clouds stay low to the ocean, held there by a temperature inversion that creates a “marine layer.”

每年夏天，北太平洋高压系统都会出现在加州海岸外，改变风向，并造成沿着海岸的冷的加利福尼亚洋流。其余的取决于饱和点和露点：水蒸气从海中升起，变成水滴，附着在空气中的微小颗粒上，如海盐气溶胶，形成云。但是这些云层悬浮在离海面不远的大气中，因为那里有一个所谓的“大气海洋层”，它是“垂直气温反转”造成的。

Sometimes this marine layer is low enough to be considered fog.

有时这个大气海洋层低到足以被认为是海雾。

“Fog is so complex,” said Alicia Torregrosa, an environmental scientist with the U.S. Geological Survey who has done deep studies on California’s coastal fog. “And the complexity has to do with thermal relationships.”

“雾是如此复杂，”美国地质调查局的环境科学家艾丽西亚·托雷格罗萨（Alicia Torregrosa）说，她对加州海雾进行了深入研究。 “而复杂性牵涉到大气热力关系。”

The start, really, is the North Pacific High. Dr. Weiss calls it “the birth of fog.”

加州海雾真正的起因是北太平洋高压。 魏斯（Weiss） 博士称其为“雾的起源”。
 

As the world warms, however, this balance could be at risk, with unpredictable consequences.

然而，随着地球变暖，这种平衡可能会面临风险，带来不可预测的后果。

“What I want to know is, do we expect more or less clouds with climate change,” Dr. Clemesha said. “I still don’t know enough to say confidently. It’s complicated.”

“我想知道的是，随着气候变化，我们预计会有更多或更少的云，”克莱梅沙（Clemesha）博士说。 “以我现有的知识，我仍然无法自信地回答这个问题。因为情况很复杂。”

Otto Klemm, a professor of climatology at the University of Münster in Germany, is more certain. He has studied data from airports all over the world.

德国明斯特大学气候学教授奥托·克莱姆（Otto Klemm）则非常肯定。他研究了来自世界各地机场的数据。

“Fog has decreased, more or less everywhere,” he said, attributing the link both to climate change and to lower levels of air pollution, as water droplets have fewer particulates to cling to. “Of about 1,000 stations, 600 or 700 show a statistically significant decrease. All over Europe, all over North America, South America — everywhere.”

他说：“雾在各地或多或少都在减少，”他将这种联系归因于气候变化和空气污染的改进，因为水滴可以附着的颗粒更少。 “在大约 1,000 个站点中，有 600 或 700 个显示出统计学上有意义的减少。遍布欧洲、北美、南美——无处不在。”

But back to California, and the fog along the coast.

让我们回到加州，继续谈论它沿岸的海雾。

“We know that the planet is warming, we know that oceans are getting warmer,” said Travis O’Brien, an assistant professor of earth and atmospheric sciences at Indiana University who has studied the California coast extensively. “What we don’t know is what’s happening in the really near coastal environment. In particular, ocean temperatures right along the coasts are a big question mark, and they have long been thought to be really important for coastal fog.”

“我们知道地球正在变暖，我们知道海洋正在变暖，”印第安纳大学地球与大气科学助理教授特拉维斯·奥布莱恩（Travis O’Brien）说；他着重研究加州海岸。 “我们不知道在靠近沿海的海洋环境中发生了什么。尤其是沿海的海温是一个很大的未知数，尽管长期以来人们一直认为它对海雾非常重要。”

Research can be contradictory or counterintuitive. A 2017 study using observational records of ships off the California coast suggests that fog is heavier than it used to be. So maybe it’s just not coming onshore the way it once was.

一些研究结果可能会有矛盾或违反直觉。2017 年的一项使用加州海岸附近船只观测记录的研究表明，雾比过去更重。所以也许海雾只是不像以前那样涌入到岸上。

In Southern California, during the periods colloquially called “May Gray” and “June Gloom,” research shows an increase in cloud-base height — low clouds persist, but are now less likely to be in the form of ground-touching fog — because of the urban heat-island effect. Some experts surmise something similar is happening in San Francisco, too.

研究表明，在南加州的俗称“五月灰蒙蒙”和“六月阴霾霾”的时期，云底高度增加——低云持续存在，但现在不太可能以接触地面的雾的形式出现——因为有城市热岛效应。一些专家推测旧金山也正在在发生类似的情况。

And maybe fog has made a comeback. Dr. O’Brien updated data from area airport observations and found that the declining fog levels in the second half of the 20th century have appeared to stabilize. Other researchers, using satellite technology, concluded this month “that the number of foggy days fluctuates considerably year-to-year with no discernible positive or negative trend occurring between 2000 and 2020.”

也许雾已经卷土重来。 奥布莱恩（O'Brien） 博士更新了地区机场观测数据，发现 在20 世纪下半叶减少的雾，似乎已经趋于稳定水平。其他使用卫星资料的研究人员在本月得出结论，“雾的天数逐年波动很大，在 2000 ～ 2020 期间，没有出现明显的正的或负的趋势。”

No one is quite sure why that is.

没有人知道为什么会是这样。

True to form and character, fog varies from day to day, minute to minute, place to place. To say that fog is increasing or decreasing depends on so many variables. Is this valley, this hill, this beach, this city as foggy as it used to be? How can you really tell?

从形式和特征来说，雾每天、每分钟、每时、每刻都在变化。说雾是增加还是减少取决于很多变量。这山谷、山丘、海滩、这座城市，是否还像从前一样雾蒙蒙的？你怎么能真的知道？

There may be no place with a deeper connection to fog than the California coast, especially the 150 miles or so from Monterey to Point Reyes National Seashore, where the lighthouse, shrouded in fog about 200 days a year, is one of the foggiest places on the continent.

可能没有比加州海岸与雾的联系更深的地方了，尤其是从蒙特雷（Monterey）到雷耶斯角（Point Reyes）国家海岸带的 150 英里左右的地方，那里的灯塔每年大约有 200 天被雾笼罩，是美国本土最有雾的地方之一。

Millions live within 50 miles of the coast along that stretch. Daily high temperatures might fall short of 60 degrees near the ocean but be more than 100 degrees inland, all depending on fog’s reach.

数百万人居住在那150 英里附近，在离海岸 50 英里的范围内。海洋附近的每日高温可能低于华氏 60 度，但内陆可能超过 华氏100 度，这一切都取决于海雾的涌入范围。

In between, many feel the effect of fog but rarely see it — a breath of cool afternoon air, maybe, or a bracing chilled wind that upends outdoor plans in the evening.

在这一地带，许多人感受到海雾的影响，但很少看到海雾——人们感觉到的，也许是一股凉爽的午后气流，或是一股令人打颤的冷风，让你不想在晚上出门。

（待续）