1 00:00:00,000 --> 00:00:04,000 Great job, you guys. 2 00:00:04,000 --> 00:00:06,000 Okay, now let's review. 3 00:00:06,000 --> 00:00:10,000 First, we learned the difference between weather and climate. 4 00:00:10,000 --> 00:00:16,000 Then, we learned how weather is produced by several factors like heat energy and moisture. 5 00:00:16,000 --> 00:00:20,000 Next, Dr. Graham Stephens told us how the CloudSat satellite 6 00:00:20,000 --> 00:00:24,000 will be able to help improve weather prediction across the globe. 7 00:00:24,000 --> 00:00:28,000 Merci beaucoup. 8 00:00:28,000 --> 00:00:33,000 Now, let's focus our attention on aerosols, climate changes, and CALIPSO. 9 00:00:33,000 --> 00:00:38,000 Now, for that, we're going to head to the Space Agency of France, or CNES. 10 00:00:38,000 --> 00:00:42,000 What NASA is to America, CNES is to France. 11 00:00:42,000 --> 00:00:45,000 So, let's go speak with Dr. Didier Tonray. 12 00:00:45,000 --> 00:00:51,000 He's a principal investigator of Parasol and a co-investigator for the CALIPSO mission. 13 00:00:51,000 --> 00:01:00,000 The CALIPSO is a satellite that's being built by both France and the United States. 14 00:01:00,000 --> 00:01:02,000 Merci, Jennifer. 15 00:01:02,000 --> 00:01:06,000 The climate of the Earth has not remained constant through the course of time. 16 00:01:06,000 --> 00:01:08,000 It has changed. 17 00:01:08,000 --> 00:01:12,000 In general, living things have affected changes in climate, 18 00:01:12,000 --> 00:01:15,000 and changes in climate have affected living things. 19 00:01:15,000 --> 00:01:19,000 Working in groups, see if you can answer the following question. 20 00:01:19,000 --> 00:01:23,000 What are some reasons why our climate has changed over time? 21 00:01:23,000 --> 00:01:28,000 Teacher, you may now pause the program so students can answer the question. 22 00:01:28,000 --> 00:01:33,000 From reports of increasing temperature, we think that the Earth's climate is maybe changing. 23 00:01:33,000 --> 00:01:37,000 But the processes behind these changes are not as clear. 24 00:01:37,000 --> 00:01:41,000 Two of the biggest uncertainties in understanding and predicting climate change 25 00:01:41,000 --> 00:01:44,000 are the effect of clouds and aerosols. 26 00:01:44,000 --> 00:01:51,000 The CALIPSO, or Cloud Aerosol LiDAR and Infrared Pathfinder Observation Satellite mission, 27 00:01:51,000 --> 00:01:55,000 will help us answer significant questions about climate processes 28 00:01:55,000 --> 00:01:59,000 by providing new information on clouds and aerosols. 29 00:01:59,000 --> 00:02:02,000 Dr. Stephens provided you with some information on clouds, 30 00:02:02,000 --> 00:02:05,000 so now let's concentrate on aerosols. 31 00:02:05,000 --> 00:02:07,000 What are aerosols? 32 00:02:07,000 --> 00:02:10,000 Aerosols are tiny particles suspended in the air. 33 00:02:10,000 --> 00:02:17,000 Some occur naturally, originating from volcanoes, dust storms, forests and grassland fires, 34 00:02:17,000 --> 00:02:20,000 leaving vegetation and sea spray. 35 00:02:20,000 --> 00:02:23,000 Human activities, such as the burning of fossil fuels 36 00:02:23,000 --> 00:02:28,000 and the alteration of natural surface cover, also generate aerosols. 37 00:02:28,000 --> 00:02:32,000 Average over the globe, aerosols made by human activities 38 00:02:32,000 --> 00:02:38,000 currently account for 10% of the total amount of aerosols in our atmosphere. 39 00:02:38,000 --> 00:02:42,000 Most of that 10% is concentrated in the northern hemisphere. 40 00:02:42,000 --> 00:02:44,000 Can you think of a reason why? 41 00:02:44,000 --> 00:02:49,000 We have much to learn about the way aerosols affect global and regional climate. 42 00:02:49,000 --> 00:02:53,000 We don't know in what regions of the planet the amount of atmospheric aerosol 43 00:02:53,000 --> 00:02:57,000 is increasing, decreasing or remaining constant. 44 00:02:57,000 --> 00:03:02,000 Overall, we don't know whether aerosols are warming or cooling the planet. 45 00:03:02,000 --> 00:03:05,000 So why do we care about aerosols? 46 00:03:05,000 --> 00:03:09,000 Aerosols tend to cause cooling of the Earth's surface immediately below them. 47 00:03:09,000 --> 00:03:14,000 Because they reflect sunlight back into space, aerosols have a direct cooling effect 48 00:03:14,000 --> 00:03:18,000 by reducing the amount of solar radiation that reaches the surface. 49 00:03:18,000 --> 00:03:23,000 It is thought that aerosol cooling may partially offset expecting global warming 50 00:03:23,000 --> 00:03:29,000 that is attributed to increases in the amount of carbon dioxide and other gases from human activity. 51 00:03:29,000 --> 00:03:34,000 Did you realize if there were no aerosols in the atmosphere, there would be no clouds? 52 00:03:34,000 --> 00:03:38,000 What can you say about the relationship between clouds and aerosols? 53 00:03:38,000 --> 00:03:44,000 Aerosols are believed to have an indirect effect on climate by changing the properties of clouds. 54 00:03:44,000 --> 00:03:47,000 As aerosol concentration increases within a cloud, 55 00:03:47,000 --> 00:03:51,000 the water in the cloud gets spread over many more particles, 56 00:03:51,000 --> 00:03:55,000 each of which is correspondingly smaller. 57 00:03:55,000 --> 00:04:01,000 In this way, changing aerosols in the atmosphere can change the frequency of cloud opulence, 58 00:04:01,000 --> 00:04:04,000 cloud thickness and rainfall amounts. 59 00:04:04,000 --> 00:04:11,000 Also clouds with low aerosol concentration and few large droplets do not scatter light well 60 00:04:11,000 --> 00:04:16,000 and allow much of the sunlight to pass through and reach the surface. 61 00:04:16,000 --> 00:04:19,000 However, the high aerosol concentration in these clouds 62 00:04:19,000 --> 00:04:24,000 allow for the formation of many small liquid water droplets. 63 00:04:24,000 --> 00:04:31,000 Up to 90% of visible radiation or light is reflected back to space by such clouds 64 00:04:31,000 --> 00:04:33,000 without reaching Earth's surface. 65 00:04:33,000 --> 00:04:39,000 Probably the best-known evidence of the effect of aerosol in the atmosphere occurred in 1991. 66 00:04:39,000 --> 00:04:43,000 A severe volcanic eruption from Mount Pinatubo, Philippines, 67 00:04:43,000 --> 00:04:49,000 put an estimated 20 million tons of sulfur dioxide into the atmosphere. 68 00:04:49,000 --> 00:04:52,000 The aerosol from that eruption stayed in the atmosphere so long 69 00:04:52,000 --> 00:04:58,000 that average global temperature over the following year cooled by about half a degree. 70 00:04:58,000 --> 00:05:01,000 So earlier in the program, Jennifer was right 71 00:05:01,000 --> 00:05:06,000 that weather in the United States affects the weather here in France and all over the globe. 72 00:05:06,000 --> 00:05:08,000 And the reverse is true. 73 00:05:08,000 --> 00:05:13,000 Scientists have been observing clouds and aerosols globally from space for many years 74 00:05:13,000 --> 00:05:18,000 using sensors that measure the amount of energy leaving Earth. 75 00:05:18,000 --> 00:05:23,000 The sensors observe how clouds and aerosols vary with latitude and longitude 76 00:05:23,000 --> 00:05:27,000 but provide little information of what is inside the clouds 77 00:05:27,000 --> 00:05:30,000 or on how they vary with altitude. 78 00:05:30,000 --> 00:05:36,000 For the first time, the CADIPSO satellite will provide vertical, pertinent images of the atmosphere 79 00:05:36,000 --> 00:05:39,000 on a global scale using a LiDAR. 80 00:05:39,000 --> 00:05:42,000 The LiDAR technique is similar to radar in operation 81 00:05:42,000 --> 00:05:49,000 but LiDAR uses short pulses of laser light instead of radio waves to probe the atmosphere. 82 00:05:49,000 --> 00:05:55,000 The LiDAR data from CADIPSO will allow us to determine precisely the altitudes of clouds 83 00:05:55,000 --> 00:05:58,000 and aerosol layers and the extent of layer overlap 84 00:05:58,000 --> 00:06:04,000 to identify the composition of clouds and to estimate the abundance and sizes of aerosols. 85 00:06:04,000 --> 00:06:09,000 CADIPSO gives us a highly advanced research tool to study the Earth's atmosphere 86 00:06:09,000 --> 00:06:14,000 and will provide the international community with a dataset that is essential 87 00:06:14,000 --> 00:06:17,000 for a better understanding of the Earth's climate. 88 00:06:17,000 --> 00:06:20,000 With more confidence in climate model predictions, 89 00:06:20,000 --> 00:06:27,000 international leaders will be able to make more informed policy decisions about global climate change. 90 00:06:27,000 --> 00:06:30,000 So the next time you wake up on a hazy summer day, 91 00:06:30,000 --> 00:06:34,000 you can tell your friends that the haziness may be caused by a sandstorm 92 00:06:34,000 --> 00:06:39,000 or volcanic eruption that occurs halfway around the world. 93 00:06:39,000 --> 00:06:42,000 Now back to you Jennifer. Au revoir.