29 December 2008-2 January 2009

• Eye on the Tropics -- Tropical cyclone activity was reported last week in the South Indian Ocean basin as Cyclone Billy moved out over the waters west of Australia. This system intensified to a category 3 cyclone on the Saffir-Simpson Scale as it traveled to the west-southwest and then curved to the west-northwest by the end of the week. Cyclone Billy finally weakened and dissipated over the weekend. An image from the MODIS instrument on NASA's Aqua satellite shows the clouds surrounding Cyclone Billy as it traveled along the coast of western Australia early last week. [NASA Earth Observatory] Additional satellite images and a more detailed discussion on Cyclone Billy appear on the NASA Hurricane Page.
• A "leap second" lengthens 2008 -- Being a leap year, the calendar year 2008 is longer by one day because an extra day was inserted at the end of February so as to adjust the calendar that has integer days to remain relatively synchronous with the length of time that the Earth travels around the sun (365.244 mean solar days). Recently, the International Earth Rotation and Reference Systems Service announced that it will insert a "leap second" as it orders its atomic clocks to be stopped for one second at 2359Z (6:59 PM EST, 5:59 PM CST) on 31 December 2008 to readjust the time scale based on the atomic clock to the time scale based upon the rotation of the Earth with respect to the sun. Tidal friction and other natural phenomena have slowed the Earth's rotation rate by approximately 2 milliseconds per day. [US Naval Observatory]
• Increases in severe storms linked to increased temperatures -- A researcher at NASA's Jet Propulsion Laboratory recently reported that his research using 5 years of data collected by the Atmospheric Infrared Sounder (AIRS) sensor onboard NASA's Aqua satellite indicates an increase in the frequency of extremely high clouds in Earth's tropics that are associated with severe storms and torrential rainfall. He claims that the increase in these clouds can be correlated with the seasonal variations in the sea surface temperatures of the tropical oceans. [NASA JPL]

• Dust plumes across Africa -- A recent MODIS image obtained from NASA's Aqua satellite shows airborne dust being carried across the Bodele Depression in the African nation of Chad. [NASA Earth Observatory] [Editor's note: This image shows Lake Chad, which is but a small remnant of a much larger lake at approximately 4000 BC. EJH]

• Images of Earth: A year in review portfolio -- A photo gallery shows twelve stunning images of Earth obtained from NASA's Earth Observatory library during the last year. [CNN]
• Modeling radiation exposure on commercial flights -- A group of researchers from NASA's Langley Research Center, Space Environment Technologies, Inc., the National Center for Atmospheric Research (NCAR) and Dartmouth College have developed a model that can be used to predict the amount of potentially damaging solar and cosmic radiation exposure that the crews and passengers experience on commercial airline flights. [NASA LRC]
• Explosions of large life forms studied -- A group of paleontologists and ecologists at from ten research institutions have been studying the approximately million-fold increases in the maximum size of organisms at two times in Earth history, at approximately 1.6 billion and 600 million years ago. These researchers claim that these increases occurred at times that roughly corresponded with large increases in atmospheric oxygen. [EurekAlert!] [EurekAlert!]
• Reproductive spores are found to be aerodynamic -- Mycologists and applied mathematicians at Harvard University have found that the reproductive spores of many fungi species have developed aerodynamic shapes that appear to minimize frictional drag. [EurekAlert!]
• An All-Hazards Monitor--This Web portal provides the user information from NOAA on current environmental events that may pose as hazards such as tropical weather, fire weather, marine weather, severe weather, drought and floods. [NOAAWatch]
• Global and US Hazards/Climate Extremes -- A review and analysis of the global impacts of various weather-related events, including drought, floods and storms during the current month. [NCDC]
• Earthweek -- Diary of the Planet [earthweek.com] Requires Adobe Acrobat Reader.