Looking Down the Eye of Typhoon Choi-Wan

By Nancy Atkinson - September 18, 2009 at 7:14 PM UTC | Planetary Science
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[/caption] Here's a look at Typhoon Choi-Wan. This is a big storm covering a huge area, and luckily it is now weakening as it continues to move northeast over the Pacific Ocean. This image was taken on Sept. 18, 2009, by the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA's Aqua Satellite. Although the storm maintains its tightly wound symmetric shape, the striking clear eye is gone, unlike the image below, which was taken on Sept. 15. Now a category 3 storm, Choi-wan now has winds of about 200 kilometers per hour (125 miles per hour or 110 knots), whereas on the 15th, sustained winds were clocked at between 250 kilometers per hour (155 miles per hour or 135 knots) and 240 km/hr (150 mph or 130 knots), according to the Joint Typhoon Warning Center. The storm continues to skirt along the coast of Japan, causing huge waves, but is not expected to make landfall.

[caption id="attachment_40650" align="aligncenter" width="580" caption="Typhoon Choi-Wan on Sept. 15. Credit: The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA's Aqua satellite. "]

[/caption] Choi-wan was a Category 4 super typhoon in this image, and the eye is clearly visible. NASA satellite imagery showed that the tops of the thunderstorms are so high they reached the tropopause, the level of atmosphere between the troposphere and stratosphere. Those high thunderstorms mean very heavy rainfall for the area underneath. The cloud tops extended to the 200 millibar level in the atmosphere where temperatures are as cold or colder than -63 Fahrenheit.

Other infrared imagery also showed the large temperature contrast between the icy cloud tops in the storm against the warm waters in the Western Pacific Ocean that continue to power the storm.

Nancy Atkinson

Nancy Atkinson

Nancy Atkinson is a space journalist and author with a passion for telling the stories of people involved in space exploration and astronomy. She is currently retired from daily writing, but worked at Universe Today for 20 years as a writer and editor. She also contributed articles to The Planetary Society, Ad Astra (National Space Society), New Scientist and many other online outlets.

Her 2019 book, "Eight Years to the Moon: The History of the Apollo Missions,” shares the untold stories of engineers and scientists who worked behind the scenes to make the Apollo program so successful, despite the daunting odds against it. Her first book “Incredible Stories From Space: A Behind-the-Scenes Look at the Missions Changing Our View of the Cosmos” (2016) tells the stories of 37 scientists and engineers that work on several current NASA robotic missions to explore the solar system and beyond.

Nancy is also a NASA/JPL Solar System Ambassador, and through this program, she has the opportunity to share her passion of space and astronomy with children and adults through presentations and programs. Nancy's personal website is nancyatkinson.com