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Aerosols and Calipso - Contenido educativo

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Subido el 28 de mayo de 2007 por EducaMadrid

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NASA Connect segment explaining aerosols and their affect on the changes of climate and weather. The segment also explores the lidar technique in the new CALIPSO satellite.

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Great job, you guys. 00:00:00

Okay, now let's review. 00:00:04

First, we learned the difference between weather and climate. 00:00:06

Then, we learned how weather is produced by several factors like heat energy and moisture. 00:00:10

Next, Dr. Graham Stephens told us how the CloudSat satellite 00:00:16

will be able to help improve weather prediction across the globe. 00:00:20

Merci beaucoup. 00:00:24

Now, let's focus our attention on aerosols, climate changes, and CALIPSO. 00:00:28

Now, for that, we're going to head to the Space Agency of France, or CNES. 00:00:33

What NASA is to America, CNES is to France. 00:00:38

So, let's go speak with Dr. Didier Tonray. 00:00:42

He's a principal investigator of Parasol and a co-investigator for the CALIPSO mission. 00:00:45

The CALIPSO is a satellite that's being built by both France and the United States. 00:00:51

Merci, Jennifer. 00:01:00

The climate of the Earth has not remained constant through the course of time. 00:01:02

It has changed. 00:01:06

In general, living things have affected changes in climate, 00:01:08

and changes in climate have affected living things. 00:01:12

Working in groups, see if you can answer the following question. 00:01:15

What are some reasons why our climate has changed over time? 00:01:19

Teacher, you may now pause the program so students can answer the question. 00:01:23

From reports of increasing temperature, we think that the Earth's climate is maybe changing. 00:01:28

But the processes behind these changes are not as clear. 00:01:33

Two of the biggest uncertainties in understanding and predicting climate change 00:01:37

are the effect of clouds and aerosols. 00:01:41

The CALIPSO, or Cloud Aerosol LiDAR and Infrared Pathfinder Observation Satellite mission, 00:01:44

will help us answer significant questions about climate processes 00:01:51

by providing new information on clouds and aerosols. 00:01:55

Dr. Stephens provided you with some information on clouds, 00:01:59

so now let's concentrate on aerosols. 00:02:02

What are aerosols? 00:02:05

Aerosols are tiny particles suspended in the air. 00:02:07

Some occur naturally, originating from volcanoes, dust storms, forests and grassland fires, 00:02:10

leaving vegetation and sea spray. 00:02:17

Human activities, such as the burning of fossil fuels 00:02:20

and the alteration of natural surface cover, also generate aerosols. 00:02:23

Average over the globe, aerosols made by human activities 00:02:28

currently account for 10% of the total amount of aerosols in our atmosphere. 00:02:32

Most of that 10% is concentrated in the northern hemisphere. 00:02:38

Can you think of a reason why? 00:02:42

We have much to learn about the way aerosols affect global and regional climate. 00:02:44

We don't know in what regions of the planet the amount of atmospheric aerosol 00:02:49

is increasing, decreasing or remaining constant. 00:02:53

Overall, we don't know whether aerosols are warming or cooling the planet. 00:02:57

So why do we care about aerosols? 00:03:02

Aerosols tend to cause cooling of the Earth's surface immediately below them. 00:03:05

Because they reflect sunlight back into space, aerosols have a direct cooling effect 00:03:09

by reducing the amount of solar radiation that reaches the surface. 00:03:14

It is thought that aerosol cooling may partially offset expecting global warming 00:03:18

that is attributed to increases in the amount of carbon dioxide and other gases from human activity. 00:03:23

Did you realize if there were no aerosols in the atmosphere, there would be no clouds? 00:03:29

What can you say about the relationship between clouds and aerosols? 00:03:34

Aerosols are believed to have an indirect effect on climate by changing the properties of clouds. 00:03:38

As aerosol concentration increases within a cloud, 00:03:44

the water in the cloud gets spread over many more particles, 00:03:47

each of which is correspondingly smaller. 00:03:51

In this way, changing aerosols in the atmosphere can change the frequency of cloud opulence, 00:03:55

cloud thickness and rainfall amounts. 00:04:01

Also clouds with low aerosol concentration and few large droplets do not scatter light well 00:04:04

and allow much of the sunlight to pass through and reach the surface. 00:04:11

However, the high aerosol concentration in these clouds 00:04:16

allow for the formation of many small liquid water droplets. 00:04:19

Up to 90% of visible radiation or light is reflected back to space by such clouds 00:04:24

without reaching Earth's surface. 00:04:31

Probably the best-known evidence of the effect of aerosol in the atmosphere occurred in 1991. 00:04:33

A severe volcanic eruption from Mount Pinatubo, Philippines, 00:04:39

put an estimated 20 million tons of sulfur dioxide into the atmosphere. 00:04:43

The aerosol from that eruption stayed in the atmosphere so long 00:04:49

that average global temperature over the following year cooled by about half a degree. 00:04:52

So earlier in the program, Jennifer was right 00:04:58

that weather in the United States affects the weather here in France and all over the globe. 00:05:01

And the reverse is true. 00:05:06

Scientists have been observing clouds and aerosols globally from space for many years 00:05:08

using sensors that measure the amount of energy leaving Earth. 00:05:13

The sensors observe how clouds and aerosols vary with latitude and longitude 00:05:18

but provide little information of what is inside the clouds 00:05:23

or on how they vary with altitude. 00:05:27

For the first time, the CADIPSO satellite will provide vertical, pertinent images of the atmosphere 00:05:30

on a global scale using a LiDAR. 00:05:36

The LiDAR technique is similar to radar in operation 00:05:39

but LiDAR uses short pulses of laser light instead of radio waves to probe the atmosphere. 00:05:42

The LiDAR data from CADIPSO will allow us to determine precisely the altitudes of clouds 00:05:49

and aerosol layers and the extent of layer overlap 00:05:55

to identify the composition of clouds and to estimate the abundance and sizes of aerosols. 00:05:58

CADIPSO gives us a highly advanced research tool to study the Earth's atmosphere 00:06:04

and will provide the international community with a dataset that is essential 00:06:09

for a better understanding of the Earth's climate. 00:06:14

With more confidence in climate model predictions, 00:06:17

international leaders will be able to make more informed policy decisions about global climate change. 00:06:20

So the next time you wake up on a hazy summer day, 00:06:27

you can tell your friends that the haziness may be caused by a sandstorm 00:06:30

or volcanic eruption that occurs halfway around the world. 00:06:34

Now back to you Jennifer. Au revoir. 00:06:39

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Idioma/s:

Materias:

Matemáticas

Niveles educativos:

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- - Nivel Intermedio

Autor/es:

NASA LaRC Office of Education

Subido por:

EducaMadrid

Licencia:

Reconocimiento - No comercial - Sin obra derivada

Visualizaciones:

312

Fecha:

28 de mayo de 2007 - 16:53

Visibilidad:

Público

Enlace Relacionado:

NASAs center for distance learning

Duración:

06′ 42″

Relación de aspecto:

4:3 Hasta 2009 fue el estándar utilizado en la televisión PAL; muchas pantallas de ordenador y televisores usan este estándar, erróneamente llamado cuadrado, cuando en la realidad es rectangular o wide.

Resolución: