Precipitation Measurement - Ppt rate

上的所有形式的降水措施basis of vertical depth of water that would accumulate on a level surface of precipitation remained where it fell. In metric system precipitation is measure in millimeters and tenths. Any open receptacle with vertical side can be used as a gauges for measuring rainfall. These refined receptacles with vertical side can be used as a gauges for measuring rainfall.

测量降水量的雨量计是两种类型

1. 记录雨量仪
2. Non-Recording rain gauges

The main difference between these rain gauges is that with the help of recording rain gauges we get the rain recorded automatically with respect to time, so intensity of rain fall is also known whereas an observer has to take readings from non recording rain gauge for rain and he has to record the time also, for calculation of intensity of rain fall.

1.无录录雨量：

通常使用非记录雨量仪。它们不会记录数据并仅收集雨，然后在刻度圆筒中测量该收集的雨。

美国天气局的标准计有200毫米直径200毫米，高度为600毫米。雨从收集器通过收集器进入溢流罐内的圆柱形测量管中。测量管具有收集器的1/10横截面区域，因此2.5毫米下降将填充管至25mm深度。测量棒以这样的方式标记为可以测量1/10的厘米深度。以这种方式，净降雨可以测量到最接近的1毫米。预计雪时收集器和管子被移除。在外部容器或溢流中收集的雪可以熔化，倒入测量管中，然后测量。这种雨量仪是最常用的雨量仪之一。

Depth of rain=厘米收集的雨量³/area of aperture of gauges in cm³

This type of gauges measures precipitation for only a specified period. Any open receptacle with vertical sides may be used for precipitation measurement but because of varying wind and splashing effect. The measurements are not compatible unless the receptacles of same size, shape and exposed in a similar manner. The US national weather service gauges is type of non recording gauges.

• 降水方法的类型
• Precipitation factors
• 降水机制
• Hydrological Cycle
• 集水区和盆地
• Analysis of Precipitation data
• Double Mass Curve
• Theissen Isohytel method
• History
• Forms of Precipitation

It consists of:

• Collector (receiving 8" 20.3 cm diameter)
• Overflow can
• Cylindrical measuring tube of area of 1/19th of collector
• Measuring scale

测量管放置在溢流罐中和测量棒;可以测量降雨的深度。由于M-Tube的区域为1/10集电器，因此在降雨量的0.1英寸的M-TUBE中雨深雨深。在雪的情况下，将移除M管和收集器，并将雪收集，熔化并倒入M管中并测量。

2.记录仪表：

Are those which automatically record rainfall without any bottle reading. The worker is not required to record the reading but instead mechanical arrangements are there by which total rainfall is recorded automatically on graph paper. A graph of total rainfall VS time which is known as mass curve of rainfall is plotted by the gauges.

Its three types commonly used are:

1. Tipping bucket gauges
2. Weighing type gauges
3. Float recording gauges

1.小桶仪表：

In TBG the collector is funneled into two compartment buckets. When one compartment of bucket is filled with rain water it becomes over balanced and tips such that the other compartment takes its place beneath the funnel. As the bucket is tipped it automatically activates an electronic circuit. This type of gauges is not suitable for measuring snow (without heating the collector).

这种类型的仪表配有位于办公室内的遥控录像机，远离实际网站。测量仪有两个隔间，以这样的方式枢转，即一个隔间一次接收下雨。一定数量的雨（通常是0.25毫米填充一个隔室，并填充它，使其尖端，排空到储存器中，并将桶的第二个隔室带到接收器的漏斗中。由于铲斗通过每个0.25毫米倾斜时雨水采取电路，导致笔在旋转滚筒上标记。这种类型的规格不适合在不加热收集器的情况下测量雪。绘图类似于其他记录雨量仪。

2. Weighing type gauges:

它由一个存储箱组成，称重以记录质量。它重量落入桶中的雨或雪，设置在带有弹簧或杠杆平衡的平台上。铲斗的重量增加及其内容在图表上记录。记录显示降水的积累。

3. Float recording gauges:

记录浮动随着降雨量增加的崛起。必须手动清空某些仪表，而其他仪表则自动清空自动启动SIPHONS。在大多数仪表油或汞中是浮子并被放置在接收器中，但在某些情况下，接收器靠在油或汞的浴缸上，浮子测量由接收器的增加重量增加的油或汞的升高。降雨抓住冻结。浮动可能因降雨捕获冰柜而受损。

这种类型的雨量计还具有接收器和浮法室以及一些记录机构或布置。在这种类型中，雨被导致浮法室，其中包含光，空心浮子。浮子作为水平的垂直运动升高在图表上借助于浮动的笔的帮助记录在图表上。该图表缠绕在旋转时钟驱动的鼓周围。为了提供24小时的连续记录，浮子室具有非常大，或者提供一些自动装置，用于在变为满时快速地清空浮动室，然后返回图表的底部。这通常是用某种虹吸布安排完成的。当仪表记录一定的固定雨量时，这种安排激活（大多数10毫米降雨量）。雪不能通过这种雨水来衡量。

Storage guages用于频繁维修的偏远地区。衡量型储存量仪在没有任何服务的情况下运行1或2个月。

称重式存储指标are designed to operate for entire season without attention. WTSG located in heavy snowfall areas should have collectors to prevent wet snow from clinging to the inside of walls and clogging the orifice. The orifice should be above the maximum snow depth expected. Gauges are initially dry and require moisture for funnel and inside surfaces.

During rainfall of 5" to 6"/hr (12.5 to 250 mm/hr) the bucket of tipping bucket gauges tips every 6 to 7 seconds and takes about 0.3 seconds to complete the tipping procedure, during which some water is still pouring into already filled compartments. The recorded ratio is 5% too low.

• Error caused by wind in gauges reading
• 当仪表安装在地面时，它倾向于风倾斜，从而缩短沉淀。朝风向风达到更多的降水。
• Obstruction due to trees, buildings and un-even topography.

4. Measurement of Precipitation by Radar

This is a modern technique for measurement of rainfall rate. It can also detect local movement of areas of precipitation. The electromagnetic energy released and received back by radar is a measure of rainfall intensity. The measurement is appreciably affected by trees and buildings. However extent of rainfall can be estimated with reasonable accuracy. Use of radar is useful where number of rain gauges installed in an area is not sufficient.

Rain Gauge Network

• The number of rain gauges and their distribution affect the nature of collected precipitation data. The larger the number of rain guages the more representative will be the data collected. But on the other hand we have to observe other factors also, like economy of the project, accessibility of certain areas and topography of the area. So, one has to look for some optimum solution. In this regard the World Meteorological Organization (WMO) has made following recommendations for minimum number of rain gauges in a catchment:
• In comparatively flat regions of temperate, Mediterranean and Tropical Zones, the ideal is at least one station for 230 – 345 sq. miles. However one station for 345 – 1155 sq. miles is also acceptable
• In mountainous regions of Temperate, Mediterranean and Tropical Zones, the ideal is at least one station for 35 – 95 sq. miles. However one station for 95 – 385 sq. miles is also acceptable.
• In arid and polar zones, one station for 575 – 3860 sq. miles is acceptable.

Snowfall Measurement:

Snowfall is often measured with regular rain gauges. Snowfall is measured by the depth of snow using snow survey. Such survey is particularly useful in mountains.

Installation of Gauges

在安装以下积分的同时，应牢记雨量。

1. Flatter ground
2. 避免陡峭的山坡
3. Avoid sloping down towards prevailing wind
4. 网站不应该太封闭到建造或森林区域。
5. All obstruction should be avoided.
6. Interpretation of precipitation