Palm Trees and Prickly Pears

If you drive around Southern California you'll see a lot of palm trees and prickly pear cacti. If you drive around Southern Spain you will too! How did it happen that two places an ocean apart have the same desert plants? The Prickly Pear Cactus, known to scientists as 'Opuntia', is native to the American Southwest and Mexico. In Mexico they are ...

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The Importance of Cave and Karst Systems

Cave and karst systems are important for two major reasons. First, the overwhelming majority of the nation's freshwater resources is groundwater. About 25% of the groundwater is located in cave and ... Continue reading


Tobacco Mosaic Virus

We all know that AIDS, SARS and flu are all caused by viruses. Most people, however, don't realize that some of the earliest work on viruses was done on a common plant virus, Tobacco mosaic virus ... Continue reading


318 Times as Massive as Earth

What is 318 times more massive than Earth? Jupiter, the fifth planet from the Sun (next in line after Earth and Mars). Jupiter is the largest planet in our Solar System. If you decided to take a ... Continue reading


Life In The Extreme

Lowly microbes just may be the toughest living things on Earth. They have learned to survive, and indeed flourish, in the harshest environment imaginable, deep-sea rifts. These rifts are chains of ... Continue reading


Surprise! Lightning Has Big Effect On Atmospheric Chemistry

AtmosphericChemistryScientists were surprised to learn summer lightning over the U.S. significantly increases regional ozone and other gases that affect air chemistry 3 to 8 miles above Earth's surface.The amounts of ozone and nitrogen oxides created by lightning surpass those generated by human activities in that level of the atmosphere. Typically over the U.S., fossil fuel burning is the main cause of nitrogen oxides (NOx), which lead to the formation of ozone near the Earth's surface. However, above the Earth's surface in the free troposphere (3-8 miles high), during the summer months, lightning activity increases NOx by as much as 90 percent and ozone by more than 30 percent.

Depending on where ozone resides, it can protect or harm life on Earth. Most ozone resides in the stratosphere (a layer of atmosphere between 8 and 25 miles high), where it shields life on Earth from the sun's harmful ultraviolet radiation. At the surface, ozone is a harmful pollutant that causes damage to lung tissue and plants. In the troposphere (surface to 8 miles high) ozone also is a radiatively active gas that affects climate. About 77 million lightning bolts annually strike the U.S. Measurements before and after lightning strikes have confirmed the generation of nitrogen oxides in the atmosphere.

Although the largest source of NOx over the U.S. is fossil fuel burning, lightning still plays a dominant role in influencing the regional air chemistry. The explanation is NOx from fossil fuel burning is released close to the Earth's surface and is consumed rapidly by chemical reactions before being transported upward. Lightning, however, directly releases NOx throughout the entire troposphere. The lightening source over North America for NOx is sufficiently large, so that it has implications on free troposphere NOx over other parts of the world, most notably Europe, which is downwind of the U.S., given the prevailing westerly flow in the Northern Hemisphere mid-latitudes.