防雷中心

A thunderstorm is defined as convection that has at least one stroke of lightning that produces audible thunder. You may have noticed that some thunderstorms have much more lightning and thunder than others. Why is this?

There are three factors that contribute to a storm having an exceptionally large amount of lightning and thunder. Each of these will be discussed individually.

HIGH INSTABILITY RELEASE: High instability is a condition in which the ambient tropospheric temperature decreases rapidly with height, especially in the top lower to mid-levels of the troposphere. When instability is high, thunderstorm updrafts will be more intense. The stronger the thunderstorm updraft, the deeper the thunderstorm column will be. As air rises in a thunderstorm it cools. When the storm height is very high, the top of the thunderstorm will cool to very cold temperatures. This intense cooling glaciates the top of the storm and this can be seen as the thunderstorm anvil. The glaciation process produces a charge differential in the storm cloud. In cases where very rapid and intense glaciation occurs (very high CAPE), lightning and thunder will be generated to a significant degrees. All thunderstorms have ice in the upper portions of the storm. How fast the ice develops, the depth of the icy portion of the storm and how quickly the precipitation moves within the cloud are important to the lightning process. There is still much research that needs to be done to fully understand this process.

HIGH MOISTURE CONTENT: Operational meteorologists determine the potential moisture a thunderstorm will have by examining lower tropospheric dewpoint and the precipitable water (PW) in the troposphere. Since thunderstorm updrafts often begin in the lower portions of the troposphere, it is most important to examine moisture there. Dewpoints of 60 F or greater in the lower troposphere will bring significant moisture into a storm. Dewpoints of 70 F or higher in the lower troposphere are not uncommon in the warm season maritime tropical environment. Low level moisture helps in that it increases instability. This in turn helps lead to a stronger storm updraft. An increase of moisture also means more ice can be produced when the moisture begins to glaciate in the updraft. Charge differential builds up more significantly as the mass of ice and water in the thunderstorm cloud increase.

WIND SHEAR: Wind shear is wind speed changing significantly with height and/or wind direction changing significantly with height. Wind shear enables a thunderstorm to last for a longer period of time since it helps displace the updraft from the downdraft. These thunderstorms are often in the form of multi-cell storms or supercell storms. Wind shear also increases turbulence within the thunderstorm. This violent mixing of precipitation in the air could help enhance charge separation in a storm.

Typical profile for highly active lightning storm: CAPE: 3,000 J/kg or greater, low level dewpoints greater than 65 F, PW 2.00 inches or greater, change in wind speed and direction with height.

雷暴被定义为至少有一次闪电产生可听见雷声的对流。 您可能已经注意到，有些雷暴的闪电和雷声比其他雷暴多得多。为什么会这样？

有三个因素导致风暴具有异常大量的闪电和雷声。每 其中将单独讨论。

高不稳定性释放：高不稳定性是环境对流层温度降低的条件 随着高度的增加而迅速增加，特别是在对流层的顶部、中下层。当不稳定性较高时，雷暴上升气流会更加强烈。雷暴上升气流越强，雷暴越深 列将是。当空气在雷暴中上升时，它会冷却。当风暴高度非常高时，顶部 雷暴将冷却到非常低的温度。这种强烈的冷却使风暴的顶部变得冰冷，而这 可以看作是雷暴铁砧。冰川作用在风暴云中产生电荷差。 在发生非常快速和强烈的冰川作用（非常高的CAPE）的情况下，将产生闪电和雷声 在很大程度上。所有雷暴的上部都有冰。冰的速度有多快 发展，风暴冰冷部分的深度以及降水在云中移动的速度 对闪电过程很重要。还有很多研究需要 要充分理解这个过程。

高含水量：业务气象学家通过以下方式确定雷暴的潜在水分 检查对流层下部露点和对流层中的可降水 （PW）。自雷雨以来 上升气流通常从对流层的下部开始，最重要的是检查那里的水分。 对流层下部 60 F 或更高的露点会给风暴带来大量水分。露点 对流层下层的70华氏度或更高，在暖季海洋热带环境中并不少见。 低水平的水分有助于 因为它增加了不稳定性。这反过来又有助于导致更强的风暴上升气流。水分增加 这也意味着当水分在上升气流中开始冰化时，可以产生更多的冰。电荷差 随着雷暴云中冰和水质量的增加，积聚得更显着。

风切变：风切变是风速随着高度和/或风向的变化而显着变化 显着与高度有关。风切变使雷暴能够持续更长的时间，因为它 有助于将上升气流从下降气流中置换出来。 这些雷暴通常以多单体风暴的形式出现 或超级单体风暴。风切变也增加了雷暴中的湍流。这种暴力的混合 空气中的降水有助于增强风暴中的电荷分离。

高活跃雷暴的典型剖面：CAPE：3,000 J/kg 或更高，低水平露点大于 65 F， PW 2.00 英寸或更大，风速和风向随高度变化。