Cloud Study

This is the VOA Special English ENVIRONMENT REPORT.

Scientists discovered something unusual when they examined some clouds over the center of the United States. These cirrus clouds remained from a severe storm in the Pacific Ocean. The high, cold clouds contained evidence of sea salt and frozen plankton organisms. Plankton are extremely small. A microscope is usually needed to see them. The scientists say the clouds carried the ocean particles more than one-thousand kilometers across the United States.

They say this was the first time examples of microscopic marine life, like plankton, were seen inside ice crystals in the cirrus clouds of a hurricane.

American scientists Kenneth Sassen, Patrick Arnott and David Starr described their findings in a report in the Journal of Atmospheric Sciences. The American Meteorological Society publishes that journal.

The scientists used information gathered by sensing equipment in the states of Utah and Oklahoma. A research airplane gathered cloud particles over Oklahoma. The National Oceanic and Atmospheric Administration also provided information for the study.

The clouds were left from Hurricane Nora. This strong storm developed in the eastern Pacific in September nineteen-ninety-seven. Nora formed near the coast of Panama and became stronger as it moved up the Baja Peninsula of Mexico. It lost strength as it crossed into California.

Nora left an area of high clouds over the western United States. The clouds were filled with ice particles, or crystals. The report says these clouds appeared unusual. They produced circles of light over a wide area, including Utah and Oklahoma.

The scientists used these clouds to study ice crystals formed around different particles. Different nuclei affect the growth and shape of ice crystals. Winds from the storm carried sea salt and other particles high into the upper atmosphere. There, the particles froze and became ice crystals.

David Starr works at NASA's Goddard Space Flight Center in Maryland. He says understanding how ice crystals grow and take shape is important to understanding how they react to the sun. Mr. Starr says these are important processes in Earth's climate system.

This VOA Special English ENVIRONMENT REPORT was written by George Grow.