Arctic Ice

The ice in the Arctic is rapidly disappearing, and the region may have its first completely ice-free summer by 2040. Polar bears and other indigenous cultures are already suffering from sea-ice loss.

Arctic Ice Arctic Ice

Glaciers

Glaciers and mountain snows are rapidly melting. Right now, Montana's Glacer National Park has only 27 glaciers. It had 150 in 1910.

Glaciers Glaciers

Coral Reefs

Coral reefs are highly sensitive to small changes in water temperature. Up to 70% of some reefs died due to bleaching (or stress) in 1998 because of temperature changes.

Coral Reefs Coral Reefs

Temperature Change

Average world temperatures have risen 1.4 degrees Fahrenheit (0.8 degree Celsius) in the last one hundred years, much of it in the recent decade.

Temperature Change Temperature Change
 
 
Theoretical concept of Hail Print E-mail
Introduction:

Precipitation is one form of hail. Hail in other sense means falling of balls or irregular lumps of ice (hailstones), 5 mm-50 mm in diameter on average, with much larger reported from severe thunderstorms. Thunderstorms always produced by cumulonimbus. small hailstones are >5 mm in diameter. They are layered and can be irregular and clumped together.

Hail formation:

Hail forms when there is condensation nuclei such as dust, bugs, or ice crystals, when supercooled water freezes on contact. When clouds contain large numbers of supercooled water droplets, these ice nuclei grow quickly at the expense of the liquid droplets because the saturation vapor pressure over ice is slightly less than the saturation vapor pressure over water. When the hailstones grow large enough, latent heat released by further freezing may melt the outer shell of the hailstone. The growth that follows is called wet growth, which is usually more efficient because the liquid outer shell allows the stone to accrete other smaller hailstones in addition to supercooled droplets. These winds hold the rain and freeze it. As the process repeats, the hail grows increasingly larger
Ideal conditions for hail formation:
1. When there are strong thunderstorm clouds, particularly those with intense updrafts, high liquid water content, great vertical extent, large water droplets, and where a good portion of the cloud layer is below freezing (< 32 F (0 C)). The growth rate is maximized at about -13 C (9 F) then hail forms.
2. during early summer where surface temperatures are warm enough to promote the instability associated with strong thunderstorms, but the upper atmosphere is still cool enough to support ice. Accordingly, hail is actually less common in the tropics despite a much higher frequency of thunderstorms than in the midlatitudes because the atmosphere over the tropics tends to be warmer over a much greater depth. Then hail forms.
3. also when dry air into strong thunderstorms over continents can increase the frequency of hail by promoting evaporational cooling which lowers the freezing level of thunderstorm clouds giving hail a larger volume to grow in.

Deadly hailstorms:

1. several hundred pilgrims were killed by a massive hailstorm in Roopkund, Uttaranchal, India.[4].
2. $150 million in damage when softball-sized hail hit Calgary, Canada on July 28, 1981.
3. Softball-sized hail destroyed roofs and cars, causing $625 million in total damage in Denver, Colorado, USA.
4. a Labour Day thunderstorm caused $400 million worth of insurable damage in Calgary, Canada. Thirteen additional hailstorms between 1981 and 1998 caused an estimated $600 million in damage in the Calgary area alone.
5. Dallas and Fort Worth, Texas, USA, $1.1 billion insured losses on May 5, 1995.
6. $1.6 billion. 20,000 properties and 40,000 vehicles were damaged during the storm with more than 25 aircraft damaged at Sydney Airport, one person was killed while fishing after getting struck by lightning and several other people were injured. It was the costliest hailstorm to hit an Australian populated city on April 14, 1999 in New South Wales, Australia.

About Author

Author: Pacific Disaster Center


The Pacific Disaster Center's mission is to provide applied information research and support for the development of more effective policies and, programs, for the disaster management. PDC give information and help during times of natural disaster. PDC Helps people during Natural calamities


Source: ArticleTrader.com
Read more at: http://www.articletrader.com/science/environment/theoretical-concept-of-hail.html.
 
< Prev   Next >
[ Back ]

Popular of Late

Global Warming Ideas

Global warming affects everyone on the planet. It's up to all of us to make sure that global conditions are stablized so that global warming and climate change don't destroy our world. Do you have some news or an article about global warming? Send your global warming submissions to This e-mail address is being protected from spam bots, you need JavaScript enabled to view it .