How much do you really know about precipitation?

Precipitation: Types, Mechanisms, and Causes

Precipitation is any product of the condensation of atmospheric water vapor that falls from clouds due to gravitational pull.
The main forms of precipitation include drizzle, rain, sleet, snow, ice pellets, graupel, and hail.
Precipitation occurs when a portion of the atmosphere becomes saturated with water vapor, reaching 100% relative humidity, so that the water condenses and falls.
Moisture that is lifted or otherwise forced to rise over a layer of sub-freezing air at the surface may be condensed into clouds and rain, typically active when freezing rain occurs.
Precipitation is a major component of the water cycle, and is responsible for depositing fresh water on the planet.
Approximately 505,000 cubic kilometers of water falls as precipitation each year: 398,000 cubic kilometers over oceans and 107,000 cubic kilometers over land.
Mechanisms of producing precipitation include convective, stratiform, and orographic rainfall.
The main ways water vapor is added to the air are: wind convergence, precipitation or virga falling from above, daytime heating evaporating water from the surface of oceans, transpiration from plants, and lifting air over mountains.
Raindrops have sizes ranging from 5.1 to 20 millimeters mean diameter, with intensity and duration of rainfall usually inversely related.
Frozen forms of precipitation include snow, ice needles, ice pellets, hail, and graupel.
No two snowflakes are alike, as they grow at different rates and in different patterns depending on the changing temperature and humidity within the atmosphere through which they fall.
Stratiform or dynamic precipitation occurs as a consequence of slow ascent of air in synoptic systems, such as over surface cold fronts, and over and ahead of warm fronts.Precipitation: Types, Effects, and Measurement
Precipitation refers to the process by which water falls from the atmosphere to the Earth's surface in the form of rain, snow, sleet, or hail.
Convective precipitation results from the rising of warm, moist air, and is often associated with severe weather events like thunderstorms, wind damages, and hail.
Orographic precipitation occurs on the windward side of mountains due to rising air motion of moist air over the mountain ridge, resulting in adiabatic cooling and condensation. This creates a rain shadow effect on the downwind side of the mountain.
In Southwest America, the Sierra Nevada range creates the same effect as the Andes mountain range in South America, leading to the formation of the Great Basin and Mojave Deserts.
Extratropical cyclones can bring cold and dangerous conditions with heavy rain and snow, with winds exceeding 119 km/h (74 mph), and are often associated with warm fronts.
The wet, or rainy, season is the time of year when most of the average annual rainfall in a region falls, and is prevalent in areas with monsoon regimes and savanna climates.
Tropical cyclones, a source of heavy rainfall, consist of large air masses with low pressure at the center and winds blowing inward towards the center in either a clockwise or counterclockwise direction.
The highest precipitation amounts outside topography fall in the tropics, closely tied to the Intertropical Convergence Zone.
The standard way of measuring rainfall or snowfall is the standard rain gauge, which can be plastic or metal and has markings on the inner cylinder down to 0.25 mm resolution.
Other types of gauges include the wedge gauge, tipping bucket rain gauge, and weighing rain gauge, with the latter being the most expensive but accurate.
Satellite sensors work by remotely sensing precipitation and recording various parts of the electromagnetic spectrum related to the occurrence and intensity of precipitation.
The infrared estimates have rather low skill at short time and space scales, but are available very frequently, while microwave estimates have greater skill on short time and space scales than is true for infrared.
Several algorithms have been developed to combine precipitation data from multiple satellites' sensors to provide "best" estimates of precipitation on a uniform time/space grid, usually for as much of the globe as possible.Important Points about Precipitation
Precipitation is not suitable for real-time applications.
Different datasets have different formats, time/space grids, and regions of coverage.
The likelihood of an event with a specified intensity and duration is called the return period or frequency.
The Köppen classification depends on average monthly values of temperature and precipitation.
Precipitation has a dramatic effect on agriculture.
Increasing temperatures tend to increase evaporation which leads to more precipitation.
Each region of the world is going to have changes in precipitation due to their unique conditions.
The urban heat island warms cities and leads to greater upward motion, which can induce additional shower and thunderstorm activity.
The Quantitative Precipitation Forecast (QPF) is the expected amount of liquid precipitation accumulated over a specified time period over a specified area.
QPFs were used within hydrologic forecast models to simulate impact to rivers throughout the United States.
Forecast models show significant sensitivity to humidity levels within the planetary boundary layer.
Radar imagery forecasting techniques show higher skill than model forecasts within six to seven hours of the time of the radar image.