Snow is commonly formed when Water vapor undergoes deposition high in the atmosphere at a temperature of less than 0°C, and then falls to the ground. It can also be produced by hoar frost which falls from the surface on which it is formed, or falling particles of ice fog formed when the humidity in surface air freezes at very low temperatures. Snow is less dense than rain, which means the same amount of moisture will produce a greater volume of snow than it will rain. One rule of thumb is that the water in eight units of snow is equivalent to one unit of rain. See Snow density.
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【摘录雪吧】雪 |
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Snow is commonly formed when Water vapor undergoes deposition high in the atmosphere at a temperature of less than 0°C, and then falls to the ground. It can also be produced by hoar frost which falls from the surface on which it is formed, or falling particles of ice fog formed when the humidity in surface air freezes at very low temperatures. Snow is less dense than rain, which means the same amount of moisture will produce a greater volume of snow than it will rain. One rule of thumb is that the water in eight units of snow is equivalent to one unit of rain. See Snow density. |
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Occurrence |
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Permanent snow covering is affected by factors such as the degree of slope on the land, amount of snowfall and the force and nature of the winds. As temperature decreases with altitude, high mountains, even near the Equator, have permanent snow cover on their upper portions, around 5,300 m high. Examples include Mount Kilimanjaro in Tanzania and the Tropical Andes in South America; however, the only snow actually to appear on the Equator is at 4,690 m altitude of the southern slope of Volcán Cayambe in Ecuador (Google Earth images). Conversely, many regions of the Arctic and Antarctic receive very little precipitation and therefore experience little snowfall despite the bitter cold (cold air, unlike warm air, cannot take away much water vapor from the sea). Here, the snow does not melt at sea level. In addition to the dry, snowless regions of the poles, there are some mountains and volcanoes in Bolivia, Chile and Argentina that are high (4,500 m-6,900 m) and cold, but the lack of precipitation near the hyperarid Atacama Desert prevents snow from accumulating into glaciers. |
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Benefits and problems |
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In areas that normally have very little or no snow, a snow day may occur with light accumulation or even the threat of snowfall. A mudslide, flash flood, or avalanche can occur when excessive snow has accumulated on a mountain and there is a sudden change of temperature. |
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Density |
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Water equivalent is of great interest to water managers wishing to predict spring runoff and the water supply of cities downstream. Measurements are made manually at marked locations known as snow courses, and remotely using special scales called snow pillows. |
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Superlatives |
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Types of snow |
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Densely, packed material formed from snow that doesn't contain air bubbles. Depending on the snow accumulation rate, the air temperature, and the weight of the snow in the upper layers, it can take snow a few hours or a few decades to form into ice. Corn Coarse, granular wet snow. Most commonly used by skiers describing good spring snow. Corn is the result of diurnal cycle of melting and refreezing. Thundersnow A thunderstorm which produces snow as the primary form of precipitation. Powder Freshly fallen, uncompacted snow. The density and moisture content of powder snow can vary widely; snowfall in coastal regions and areas with higher humidity is usually heavier than a similarly depth of snowfall in an arid or continental region. Light, dry (low moisture content) powder snow is prized by skiers and snowboarders. It is often found in the Rocky Mountains of North America. Firn Snow which has been lying for at least a year but which has not yet consolidated into glacier ice. It is granular. Flurries A period of light snow with usually little accumulation with occasional moderate snowfall. Sleet In Britain, rain mixed with snow; in America, ice pellets formed when snowflakes pass through a layer of warm air, thaw, then refreeze on further descent. Soft hail Granules of snow or ice pellets formed when supercooled water accretes on ice crystals or snowflakes. Freezing rain Rain that freezes on impact with a sufficiently cold surface. This can cover trees in a uniform layer of very clear, shiny ice, a beautiful phenomenon, though excessive accumulation can break tree limbs and utility lines, causing utility failures and possible property damage. Snizzle A mixture of snow and drizzle. This termed was coined by a meteorologist on the Boston television station WBZ-TV.[4] Snow storm A long storm of relatively heavy snow. Snow squall A brief, very intense snowstorm. Blizzard A long-lasting snow storm with intense snowfall and usually high winds. Particularly severe storms can create whiteout conditions where visibility is reduced to less than 1 m. Lake effect snow Produced when cold winds move across long expanses of warmer lake water, picking up water vapor which freezes and is deposited on the lee shores. Snowdrift Large piles of snow which occur near walls and curbs, as the wind tends to push the snow up toward the vertical surfaces. Ground blizzard Occurs when a strong wind drives already fallen snow to create drifts and whiteouts. Packing snow Snow that is at or near the melting point, so that it can easily be packed into snowballs and hurled at other people or objects. This is perfect for snow fights and other winter fun, such as making a snowman, or a snow fort. Slush Snow which partially melts upon reaching the ground, to the point that it accumulates in puddles of partially-frozen water. Hail Many-layered ice balls, ranging from "pea" sized (0.25 in, 6 mm) to "golf ball" sized (1.75 in, 43 mm), to, in rare cases, "softball" sized or greater (>4.25 in, 108 mm). Hailstorm A storm of hail. If the hail is sufficiently large, it can cause damage to cars or even people. Artificial snow Snow can be also manufactured using snow cannons, which actually create tiny granules more like soft hail (this is sometimes called "grits" by those in the southern U.S. for its likeness to the texture of the food). In recent years, snow cannons have been produced that create more natural looking snow, but these machines are prohibitively expensive. Watermelon snow A reddish/pink colored snow that smells like watermelons, and is caused by a red colored green alga called chlamydomonas nivalis Penitentes Tall blades of snow found at high altitudes |
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回复：【摘录雪吧】雪 |
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雪 |
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雪共同地被形成当水蒸气接受证言上流在大气在温度少于0.? 并且然后落对地面。它可能由下跌从表面它被形成, 或冰雾下落的微粒被形成的灰白霜并且生产当湿气在表面空气里结冰在非常低温。雪比雨, 较不密集的意味同样相当数量湿气比它将下雨将生产雪的更加了不起的容量。一个经验法则是, 水在雪八个单位与雨一个单位是等效的。参见雪密度。 |
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发生 |
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永久雪覆盖物由因素影响譬如程度倾斜在土地, 风的相当数量降雪和力量和本质。当温度减少以高度, 高山, 在赤道附近, 有永久雪盖子在他们的上部部份, 大约5,300 m 高。例子包括登上Kilimanjaro 在坦桑尼亚和热带安地斯在南美洲; 但是, 唯一的雪实际出现在赤道是在Volc..n Cayambe 南部的倾斜的4,690 m 高度在厄瓜多尔(Google 地球图象) 。 相反地, 许多地区的北极和南极州接受很少降雨雪和因此经验小的降雪尽管苦涩寒冷(冷空气, 不同于温暖的空气, 无法拿走水蒸气从海) 。这里, 雪不熔化在海平面。除杆之外的干燥, snowless 地区, 有是高的一些山和火山在玻利维亚、智利和阿根廷(4,500 m-6,900 m) 和冷, 但缺乏降雨雪在hyperarid Atacama 沙漠附近防止雪积累入冰川。 |
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好处和问题 |
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在通常有非常一点点或没有雪的区域, 一雪天也许发生以轻的储积甚至降雪威胁。mudslide 、暴洪, 或雪崩可能发生当过份雪积累了在山并且有一种突然的温度变化。 |
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雪花 |
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几何 雪花总有六条相称胳膊(沿三个相称轴), 出现从普通的冰六角晶体结构(以冰Ih 著名) 沿它的'basal' 飞机。 有, 宽广地, 二个可能的解释为雪花对称。首先, 那里能是通信或信息传递在胳膊之间, 这样, 成长在各条胳膊里影响成长在彼此胳膊。表面张力或声子是在这样的通信能发生的方法之中。 另一解释, 看来是流行看法, 是, 雪花的胳膊独立地增长在应该迅速地变化在温度、湿气和其它大气情况的环境里。这个环境由反应相对地空间地认为是同类的在唯一剥落的等级, 导致胳膊成长为一个高水平视觉相似性用相同方式相同情况, 相似, 无关的树反应环境变动由生长近相同套年轮。区别在环境里在标度大比雪花导致被观察的缺乏交互作用在不同的雪花之间形状。 但是, 概念, 二雪花不是象不一定是真实的。严格上讲, 它是极端不太可能为任何二个对象在宇宙包含一个相同分子结构; 但, 有, 仍然, 防止它的没有已知的科学法律。在更加重实效的感觉, it's 可能, 虽然不更多, 二雪花是视觉上相同的如果他们的环境足够相似, 或者因为他们非常增长在互相附近, 或简单地偶然。美国气象学会报告, 匹配的雪水晶由全国中心的南希骑士大气研究的发现了。水晶不是剥落在通常感觉而是相当空心六角棱镜里。 |
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密度 |
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水等值是巨大利益浇灌经理希望预言春天决赛和城市供水顺流。测量手工被传达在明显地点当雪路线, 并且使用特别标度遥远地叫雪枕头。 |
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最高级 |
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某种休闲的形式依靠雪 |
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演奏与雪撬或乘坐在sleigh 修造雪人或雪堡垒 投掷的雪球相互在一次雪球战斗或在其他方面戏弄他们。(人似乎是唯一是投掷他们的雪球。矮小黑猩猩知道运载雪球, 但从未投掷他们。) 做雪天使 那里雪是缺乏的但温度是足够低, 雪大炮也许被使用导致充分数额为这样体育。world's 最大的snowcastle 被建立在Kemi, 芬兰, 每个冬天。 |
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类型雪----冰 |
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玉米 粗糙, 颗粒状湿雪。最常用由滑雪者描述好春天雪。玉米是熔化和重新冷冻的昼夜周期的结果。 Thundersnow 生产雪作为降雨雪的主要形式的雷暴。 粉末 新鲜地下落, uncompacted 雪。粉末雪密度和湿气含量可能广泛变化; 降雪在海岸地带和区域以更高的湿度比降雪的深度相似地通常重的在一个干旱或大陆区域。轻, 干燥(低湿度含量) 粉末雪是得奖的由滑雪者和挡雪板。它经常被发现在北美洲岩石山。 Firn 说谎至少一年未巩固入冰川冰的雪但。它颗粒状。 慌张 小雪的期间以通常一点储积以偶尔的适度降雪。 雨夹雪 在不列颠, 下雨混杂与雪; 在美国, 冰药丸形成了当雪花通过温暖的空气层数, 解冻, 然后重新冷冻在进一步下降。 软的冰雹 雪或冰药丸粒子被形成当超冷的水共同生长在冰晶或雪花。 结冰的雨 下雨结冰在冲击以充足地冷的表面。这可能盖树在非常清楚, 发光的冰, 一种美好的现象一致的层数, 虽然过份储积可能打破树枝和公共线, 造成公共失败和可能的财产损害。 Snizzle 雪和毛毛雨混合物。这被命名由一个气象学家铸造了在波士顿电视台WBZ-TV.[4 ] 雪风暴 相对地大雪一场长的风暴。 雪急风 摘要, 非常强烈的暴风雪。 飞雪 一场持久雪风暴与强烈的降雪和通常大风。特殊剧烈风暴可能创造可见性被减少到少于1 m 的whiteout 条件。 湖作用雪 生产当寒风行动横跨更加温暖的湖水长的浩瀚, 采摘水蒸气结冰和被放置在庇护支持。 随风飘飞的雪 发生在墙壁和遏制附近的大堆雪, 如同风倾向于推挤雪朝垂直的表面。 地面飞雪 发生当猛烈的风驾驶已经下落的雪创造漂泊和whiteouts 。 包装雪 下雪是在或者靠近熔点, 以便它可能容易地被包装入雪球和用力投掷在人民或对象。这对雪战斗和其它冬天乐趣, 譬如做雪人, 或雪堡垒是完善。 融雪 部份地熔化在到达地面的雪, 对它积累在部份冻水水坑的点。 冰雹 许多层状冰球, 范围从"pea" 估量(0.25寸, 6 毫米) 对"golf ball" 估量(1.75 寸, 43 毫米),对, 在罕见的案件, "softball" 估量或更加伟大(>4.25, 108 毫米) 。 雹暴 冰雹风暴。如果冰雹是充足地大的, 它可能造成对汽车甚至众人的损伤。 人为雪 雪可能并且被制造使用雪大炮, 实际上创造微小的粒子更象软的冰雹(这有时叫做"grits" 由那些在南部的美国为它的相像对食物的纹理) 。近年来, 创造更加自然的看的雪的雪大炮被生产了, 但这些机器是禁止地昂贵的。 西瓜雪 reddish/pink 上色了嗅到象西瓜的雪, 并且由一个红色色的绿色海藻造成叫做chlamydomonas nivalis Penitentes 雪高刀片发现了在高处 |
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回复：【摘录雪吧】雪 |
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欣赏欣赏吧 呵呵 |
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The first snow came |
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All white save the river, that marked its course by a winding black line across the landscape; and the leafless trees, that against the leaden sky now revealed more fully the wonderful beauty and intricacies of their branches. What silence, too, came with the snow, and what seclusion! Every sound was muffled, every noise changed to something soft and musical. No more tramping hoofs, no more rattling wheels! Only the chiming of sleigh-bells, beating as swift and merrily as the hearts of children |
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回复：【摘录雪吧】雪 |
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～0～ |
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