Research and Application News
NASA sees Hurricane Cristina making a reverse in strength
13 June 2014
Hurricane Cristina intensified rapidly on 12 June and infrared satellite data showed cloud top temperatures became extremely cold as thunderstorms towered to the top of the troposphere. One day later, Cristina was weakening quickly and infrared data showed cloud top temperatures were warming as the cloud tops dropped.
Infrared data basically reads a cloud top's temperature. When NASA's Aqua satellite passed over Hurricane Cristina early on 12 June, cloud top temperatures exceeded -80C (-112F). Today, 13 June, infrared data showed cloud top temperatures had warmed to near -53C (-63F) over a large area of the storm as cloud heights dropped. Cloud heights dropped because the convection had weakened.
Basically, convection occurs when a parcel of air near the Earth's surface is heated, it rises (making it lighter than the surrounding air). As convection continues the air pressure begins to fall, and the parcel of air expands. When that happens, the air consumes heat energy and temperature in the parcel falls. When the parcel of air cools enough and reaches the dew point, clouds form (condensation occurs). If the air is unstable, that convection will continue at much higher levels in the atmosphere and it can create towering thunderstorms.
Image credit: NASA/NOAA GOES Project - Hurricane Cristina, as seen by GOES-West