1 00:00:00,000 --> 00:00:03,000 Hello, Dr. Brau? 2 00:00:03,000 --> 00:00:06,000 Oh, hello. You must be one of the treehouse detectives. 3 00:00:06,000 --> 00:00:09,000 I just spoke with Dr. D on the phone, and he said you were coming over. 4 00:00:09,000 --> 00:00:14,000 We're trying to figure out how scientists can predict if a tropical storm will get bigger or smaller. 5 00:00:14,000 --> 00:00:16,000 I definitely can help you with that. 6 00:00:16,000 --> 00:00:21,000 We learned about LIDAR before, but we could use a review. Can you help us? 7 00:00:21,000 --> 00:00:25,000 Certainly. LIDAR is an acronym that stands for Light Detection and Ranging. 8 00:00:25,000 --> 00:00:29,000 It's a pulsating instrument that is used to probe the atmosphere. 9 00:00:29,000 --> 00:00:32,000 Let's take a look now at how laser light scatters in the atmosphere. 10 00:00:32,000 --> 00:00:35,000 You've seen a laser pointer before. 11 00:00:35,000 --> 00:00:39,000 If you would pass the beam from the pointer through this plume from the vaporizer, 12 00:00:39,000 --> 00:00:44,000 you'll see the scattering from the small particles, just like a LIDAR sees in the atmosphere. 13 00:00:44,000 --> 00:00:46,000 Wow, this is neat. 14 00:00:46,000 --> 00:00:52,000 And if you would imagine using a pulsed laser, we could see where the scattering is and how much is there, 15 00:00:52,000 --> 00:00:54,000 much like a laser radar. 16 00:00:54,000 --> 00:00:57,000 But how do you measure water vapor with a LIDAR? 17 00:00:57,000 --> 00:00:59,000 Well, come on, let me show you. 18 00:01:01,000 --> 00:01:04,000 Take a look at these two laser beams. 19 00:01:04,000 --> 00:01:09,000 Now you can slide the container of colored water into the two beams and see what happens. 20 00:01:11,000 --> 00:01:14,000 The green laser light almost disappears. 21 00:01:14,000 --> 00:01:19,000 Exactly. And by comparing the intensity and how much changes in the green light, 22 00:01:19,000 --> 00:01:22,000 we can calculate how much dye is in the cell. 23 00:01:22,000 --> 00:01:25,000 So you mean you can detect the amount of water vapor 24 00:01:25,000 --> 00:01:29,000 by comparing how two laser lights change when water vapor is present? 25 00:01:29,000 --> 00:01:33,000 Exactly. Let's go see a LIDAR that's flown around a hurricane. 26 00:01:36,000 --> 00:01:39,000 This LIDAR system is called LASE. 27 00:01:39,000 --> 00:01:43,000 LASE stands for LIDAR Atmospheric Sensing Experiment, 28 00:01:43,000 --> 00:01:47,000 and it was designed to go onto a very high-altitude airplane. 29 00:01:47,000 --> 00:01:50,000 When LASE is flown on an airplane around a hurricane, 30 00:01:50,000 --> 00:01:54,000 we can make measurements of how much water vapor is flowing into the hurricane. 31 00:01:54,000 --> 00:01:56,000 We learned that water vapor feeds the storm. 32 00:01:56,000 --> 00:02:01,000 You're right. Water vapor is the primary energy source that drives the hurricane. 33 00:02:01,000 --> 00:02:04,000 Why would NASA want to fly around hurricanes? 34 00:02:04,000 --> 00:02:06,000 The information we gather with our experiments 35 00:02:06,000 --> 00:02:09,000 should help us to better predict hurricane behavior. 36 00:02:09,000 --> 00:02:12,000 And we hope to develop very small LIDAR systems 37 00:02:12,000 --> 00:02:18,000 that can go on unmanned aerial vehicles, or UAVs, which are small model aircraft. 38 00:02:18,000 --> 00:02:21,000 Why would you want to put LIDAR on such small planes? 39 00:02:21,000 --> 00:02:25,000 Well, a UAV can fly around a hurricane for several days 40 00:02:25,000 --> 00:02:30,000 and get the information we need to help better predict what the hurricane will do. 41 00:02:30,000 --> 00:02:35,000 In the future, we hope to develop a LIDAR system to go into space to do the same thing. 42 00:02:35,000 --> 00:02:37,000 Wow. That would be really awesome. 43 00:02:37,000 --> 00:02:40,000 Thanks, Dr. Brouwer. You've been a big help.