SATELLITE IMAGERY PRACTICE

#1 Here are three full-earth visible satellite images ( Image 1, Image 2, and Image 3) from one of the European geostationary satellites that sits over the prime meridian ( 0o longitude). Each image was taken at 0600 UTC (Greenwich time), which, in that part of the world, is around the time of sunrise. The images were taken on three different dates: one around the Northern Hemisphere summer solstice, one around the Southern Hemisphere summer solstice, and the other around one of the equinoxes. Match each its image to its appropriate date, and explain how you arrived at your answer. (The clues are the orientation of the Circle of Illumination (boundary that separates day from night) and how much of the northern and southern hemispheres are bathed in sunlight.

#2.Consider this infrared satellite image at 1145Z on a mid-November day, showing portions of the western Gulf States. What was the local time in Central Standard Time? b. Was the sky cloudy or clear over most of Mississippi? (Explain your answer using principles of infrared satellite imagery). c. Was the sky cloudy or clear over most of Louisiana and eastern Texas? (Again, explain your answer using principles of infrared satellite imagery).

#3. Here are visible and infrared satellite images from 1745 UTC on December 10, 2009 over parts of the central and southern Plains. Look carefully at the visible image. What evidence is there that much, if not all, of the white you see is snow cover? (Particularly look at Iowa, northern Nebraska, and northern Kansas, and consider what month it is). Briefly explain your answer. b. Now look carefully at the infrared image. What evidence is there that could help you tell the difference between where snow is on the ground and where there is no snow (particularly in Kansas and Missouri)? Explain your answer: what is it about the snow cover (as compared to where there is no snow cover) that creates this difference? c. Now consider this map of maximum temperatures that day, and focus on Kansas and Missouri. What evidence exists to support your answer in part (b)?

#4. Here are three satellite images from 1800 UTC on June 11, 2015: visible, infrared, and water vapor. To do this problem, you will also need to refer to this Figure 5.17. Consider the ocean just off the coast of northern Baja California. Which column in Figure 5.17 (1, 2, 3 or 4) corresponds best to atmospheric conditions (clouds and/or water vapor) in this area? Explain your answer. b. Consider Baja California and the Gulf of California (the water body between Baja and Mexico). Which column in Figure 5.17 (1, 2, 3 or 4) corresponds best to atmospheric conditions (clouds and/or water vapor) in this area? Explain. c. Consider the same area as in part (b) but focus on the infrared image. Explain why Baja California looks different than the Gulf of California in this image.

#5. Now focus on the state of Oregon in the image: visible #5. Now focus on the state of Oregon in the image: visible. Skies were nearly completely clear over the state that day (so you are seeing the surface of the earth), but notice on the visible image that there are subtle variations in shading (here is a close-up). Explain these variations, using this true-color satellite image of that area taken on another clear day. (True color images more vividly capture variations in surface covering as would occur, for example, between relatively moist forested areas and dry areas with little vegetation).

#6. Consider this true-color satellite image from June 9, 2015. What kind of weather satellite (geostationary or polar-orbiting) collected the data to create this satellite image? How do you know? b. Skies over southern Lake Michigan, northern Indiana, and central Ohio were actually cloud-free at this time, but the sky looks hazy on the visible image. To figure out what this haze was, consider abbreviated station models from about 36 hours earlier from the northern part of the Canadian provinces of Saskatchewan and Manitoba. What obstruction to visibility is being reported ? c. Now consider this chart which shows winds a few thousand feet above the surface at that time. In what direction would the obstruction to visibility you identified in part (b) tend to move? Is that consistent with what you observe on the June 9 satellite image?

#7. In southern California, a warm dry east or northeast wind that descends (downslopes) from the elevated desert plateaus is called a Santa Ana. Such winds easily dry out vegetation and heighten the risk for a particular phenomenon. Consider this animation of visible satellite imagery from 1500 UTC on May 14, 2014 to 200 UTC on May 15, 2014. Look at this surface map from 2100 UTC on May 14, 2014; zoom into Southern California, focusing on the station models. What is the general range of temperatures at this time in southern California ? (Look only at stations on land, not offshore, and consider only the southernmost ten or so stations). Then, just to emphasize an important point for this problem, write down the dew points at these locations, making sure to include in your answer the lowest dew point. b. What does the dew-point depression at these locations tell you about the relative humidity of the air in southern California? c. Based on your answers above, what do you think is being detected by the visible satellite image that is blowing offshore in southern California and northern Mexico at this time, and what caused it? Hint: The obstruction is being reported at one of the stations in southern California at this time.

8. Visible image below shows cloud clover in NW Ohio 8. Visible image below shows cloud clover in NW Ohio. What is the height of these clouds? Explain your reasoning. INFRARED VISIBLE WATER VAPOR

9. Below are radar images of Duluth 9. Below are radar images of Duluth. Which image is base reflectivity and which is composite reflectivity?

10. The visible image shows clouds over NE MN 10. The visible image shows clouds over NE MN. What evidence do you have that those clouds represent rising air in a low pressure trough? visible Water vapor Forecast map 11. Can you associate any of the clouds or water vapor patterns with any fronts on the forecast map?

12 a) Go to National Weather Service Duluth page. Click on radar 12 a) Go to National Weather Service Duluth page. Click on radar. Describe the pattern in precipitation that you see. 12 b) Toggle the lakes, rivers, cities, counties, topography on and off. Compare the composite and base reflectivity images. Explain the differences that you see. 12 c) Look at the Base Velocity Image as a Looped image. What direction is the wind? (Remember, wind is named in the direction it is coming FROM).

13. For this problem, you will need several weather charts from 12 UTC on October 3, 2014, including a surface map, infrared satellite image, and radar reflectivity image. What is the local time in Duluth (see the radar image)? b. Describe (using at least half a dozen state references) where the highest cloud tops are in the United States. How do you decide? c. Describe the general relationship between the location of precipitation, the location of the highest cloud tops, and the location of surface low-pressure systems and fronts (the lines with blue triangles and red semicircles on them). d. Parts of what state are likely receiving the most intense rainfall? Justify your answer.