Lab Exercises: Universal Time Coordinated 1. A satellite image of the United States was taken at "0900 What was the local standard time in Chicago (90°W)? a day-at times surface weather maps are prepared by the Canadian Meteorological Centre fo in Calgary, AB, during the winter (standard time) and the summer (daylight time) 06002, 1200z 1800z. Equate each of these times to the local time Cloudless area off the coast of Oregon 0600z Local Calgary Time (winter) Local Calgary Time (summer) (b) Infrared 1200z 1800z D. Weather Satellite Images Geostationary Operational Environmental Satellites (GOES) orbit at fixed locations relative to the Earth's surface. The satellites transmit images that are used for weather forecasting The sensors on GOES satellites detect various wavelengths of radiation. The intensity of radiation in cach wavelength is recorded and used to produce images. The images below (following pages) demonstrate weather satellite images created from visible light, thermal infrared radiation, and a portion of the infrared spectrum that allows the creation of "water vapor" images Visible light satellite images show light reflected off Earth's surface or by clouds. The brightness of the image depends on the albedo of the reflecting surface, with bright surfaces being snow and ice-covered surfaces or the tops of clouds (low or high clouds), and dark surfaces being land areas and the oceans. Infrared satellite images show longwave thermal infrared radiation emitted by Earth's surface or by clouds. Radiation laws equate the amount of radiation emitted to temperature thus infrared images show differences in the temperature of surfaces. On infrared satellite images, cooler surfaces are shown in white and warmer surface in black. The tops of high cumulonimbus clouds are much colder than low clouds of fog, and so a temperature of low clouds and fog may be sim Ppear bright white on infrared images. The same darker shade. to the surface temperature and appear as the Water vapour satellite images are able to let us see regions of moist and dry air in the middle and upper troposphere, with darker shades showing areas of relatively dry air and lighter shades arcas of relatively moist air. (a) Visible Light Clouds off the coast of California (c) Water Vapor GOES-West visible light (a), infrared (b), and water vapor (c) images taken on September 26, 2003 (a) 0300Z 16 (b) 1200Z Infrared satellite images taken on January 23, 2013, at an interval of 9 hours (0300z and 12002). Lab Exercises: Weather Satellite Images 1. a) In the visible light and infrared images of the northern Pacific and west coast of North America from December 29, 2012 (above), circle the well-developed mid-latitude cyclone b) Are the clouds along the cold front of the mid-latitude cyclone low or high clouds? How can you tell? DESIS VIS 29-Dec-2012 21001 Naval Research Laboratory c) Why does a portion of southern Mexico appear dark in the Dec 29, 2012, infrared image? 2. Use the September 26, 2003, composite image panel (above) to answer the following: a) In the visible light image, are the clouds off the coast of Califomia low clouds or high clouds? How can you tell? b) In the visible light image there is a cloudless area off the coast of Oregon. Is this a region of relatively moist or relatively dry air? c) Why might explain why there is a lack of clouds in this area? There are several possible answers. (Hint: think about the processes or conditions that cause clouds to form) 3. Use the January 23, 2013, pair of infrared satellite images (above) to answer the following: a) Why do northern and southern Africa appear much darker in the 1200z image than in the 0300z image? (what do the images tell you about temperature and why does it change?) b) Has the ocean around the African continent changed temperature during the time between the first and second image? Explain why it has or has not changed. Visible light image from GOES-West. Dec 29, 2012, 2100z GOESIS IR 29-Dec-2012 21001 Naval Research Laboratory c) Which feature of the general atmospheric circulation explains the band of clouds near the equator? d) Why are these clouds much more developed in the 1200z image than in the 0300z image? -60 nfrared image from GOES-West. Dec 29, 2012, 2100z