* Radius of a sphere with the same mass - PowerPoint PPT Presentation

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* Radius of a sphere with the same mass

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  1. The Shape of Raindrops The common perception that raindrops are teardrop-shaped is wrong. (Breaks up into smaller drops) <1mm* 2mm* 3mm* Move the mouse pointer over each raindrop shape to see more details >4.5mm* References * Radius of a sphere with the same mass

  2. The Shape of Raindrops The common perception that raindrops are teardrop-shaped is wrong. <1mm* In a small raindrop, the surface tension of water molecules is strong enough to pull the drop to form a sphere 2mm* 3mm* >4.5mm* References * Radius of a sphere with the same mass

  3. The Shape of Raindrops The common perception that raindrops are teardrop-shaped is wrong. LOW PRESSURE LOW PRESSURE <1mm* HIGH PRESSURE Air flow HIGH PRESSURE 2mm* Air flow 3mm* • The larger the raindrop, the weaker the surface tension. • As a larger raindrop falls faster, air pressure will build up at the bottom of the drop so that the bottom of the drop will be flattened, or even develop a depression. • The pressure just above the drop (or called “wake”) is relatively lower so that the top portion of the drop is being “sucked” upwards. >4.5mm* References * Radius of a sphere with the same mass

  4. The Shape of Raindrops The common perception that raindrops are teardrop-shaped is wrong. (Breaks up into smaller drops) <1mm* 2mm* 3mm* >4.5mm* • When a drop is very large, the surface tension is completely overwhelmed and it can be blown inside out to form “a bag with an annular ring of water and then break up into smaller drops” (Fraser). References * Radius of a sphere with the same mass

  5. References • Cramer, M.S. (2004). The Shape of Raindrops. Retrieved from http://www.fluidmech.net/ tutorials/raindrops/raindrop.htm • Fraser, A.B. (n.d.). Bad Rain. Retrieved from http://www.ems.psu.edu/~fraser/Bad/BadRain.html • Heidorn, K.C. (July 1, 2000). Weather Almanac for July 2000 - Raindrops, So Many Raindrops. Retrieved from http://www.islandnet.com/~see/weather/almanac/arc2000/alm00jul.htm • U.S. Geological Survey (September 14, 2005). Are raindrops shaped like teardrops? Retrieved from http://ga.water.usgs.gov/edu/raindropshape.html