February 17 th Video Conference Agenda

Transcription

1 February 17 th Video Conference Agenda 8:30 am Video, audio and connection checks 9:00 am Brief intro by mediator, Ellen Holmes, followed by 3 to 5 minute Day in the Life of Presentations from each school. (Q&A as occurs) 9:15 am Introduction of NASA scientists and PI s, mission overviews (Q&A as occurs) 9:25 am Introduction of Challenge Questions and student work time 9:50 am Presentation of Answers (3 minutes per 5 groups per class) 10:20 am Presentation of Experts in regards to challenge questions (Q&A as occurs) Challenge Questions: (Not to be revealed to students and teachers until the event) How will cloud conditions change if Earth s surface becomes warmer on average? If the surface water of oceans and lakes warms, more water will evaporate. This should increase the total amount of water in the atmosphere and the amount of cloud cover, but what type of clouds will form? Will the increase in clouds happen mostly at high altitudes or low altitudes? CALIPSO / CloudSat February 17, 2004 Videoconference Materials 1

2 Student Activities for February 17 th Video Conference Class Presentation Each class will have 3 to 5 minutes to present the culture of their school and community. These productions can be as simple or as technical as the teachers and students choose. Your presentation should give the other school a sense of what a typical day would be like for students. It might go beyond the school to include a sense of the surrounding community. Have fun and be creative! Multimedia presentations should be sent directly to NASA Langley so that we can run them from our computers to help eliminate production glitches. Keep in mind that the presentation you make will be viewed over a video monitor, use high contrast colors between text and background, keep text to a minimum, simple, and relatively large. Background Information for Lessons 1 & 2 The importance of clouds and aerosols to climate change Everything, from an individual person to Earth as a whole, emits energy. Scientists refer to this energy as radiation. As Earth absorbs incoming sunlight, it warms up. The planet must emit some of this warmth into space or increase in temperature. Two components make up the Earth's outgoing energy: heat (or thermal radiation) that the Earth's surface and atmosphere emit; and sunlight (or solar radiation) that the land, ocean, clouds and aerosols reflect back to space. The balance between incoming sunlight and outgoing energy determines the planet's temperature and, ultimately, climate. Both natural and human induced changes affect this balance, called the Earth's radiation budget. Earth's radiation budget is a balance between incoming and outgoing radiation. Clouds affect the radiation budget directly by reflecting sunlight into space (cooling the Earth) or absorbing sunlight and heat emitted by the Earth. When clouds absorb sunlight and heat, less energy escapes to space and the planet warms. To understand how clouds impact the energy CALIPSO / CloudSat February 17, 2004 Videoconference Materials 2

3 budget, scientists need to know the composition of cloud particles, the altitude of clouds and the extent to which clouds at different altitudes overlap each other. Both natural processes and human activities produce aerosols. They either reflect or absorb energy, depending on their size, chemical composition and altitude. The haze layer that is commonly seen in the summertime is one example of an aerosol that primarily reflects sunlight. Soot emitted by diesel engines is an example of an aerosol that absorbs sunlight. The reflection and absorption of energy by aerosols act in a direct way to change the balance between incoming and outgoing energy. These effects are called direct aerosol radiative forcing. White cloud streaks over the northern Pacific Ocean stem from aerosols emitted into the atmosphere in exhaust from ship engines. Small water or cloud droplets form around these added aerosols, increasing the brightness of clouds over the ship tracks as compared to the surrounding clouds. This example illustrates the indirect effect of aerosols on the Earth's radiation budget. This image was acquired by the Moderate resolution Imaging Spectroradiometer (MODIS), flying aboard NASA's Terra satellite, on April 29, (Image courtesy Jacques Descloitres, MODIS Land Rapid Response Team at NASA GSFC). Smoke plumes, such as those from wildfires in Russia shown above, contain aerosols that directly affect the Earth's radiation budget. This Moderate Resolution Imaging Spectroradiometer (MODIS) image from May 15, 2002 also shows extensive, dark burn scars along with actively burning fires (red dots) on the north side of the Amur River, which separates Russia (north) and China (south). (Image courtesy Jacques Descloitres, MODIS Land Rapid Response Team at NASA GSFC). Aerosols also can affect the Earth's radiation budget indirectly by modifying the characteristics of clouds. Cloud particles almost always form around aerosols such as natural sea salt particles or human made sulfate particles. The presence of additional aerosols can change the way clouds radiate energy and the length of time they stay intact. A good example is the way that exhaust CALIPSO / CloudSat February 17, 2004 Videoconference Materials 3

4 particles emitted into the atmosphere by ships can increase the brightness of clouds along their course. These effects are called indirect aerosol radiative forcing. Clouds and Climate Clouds play a complex role in climate. They are the source of precipitation, affect the amount of energy from the sun that reaches Earth s surface, and insulate Earth s surface and lower atmosphere. At any given time, over half of Earth s surface is shadowed by clouds. Clouds reflect some of the sunlight away from Earth, keeping the planet cooler than it would be otherwise. At the same time, clouds absorb some of the heat energy given off by Earth s surface and release some of this heat back toward the ground, keeping Earth s surface warmer than it would be otherwise. Satellite measurements have shown that, on average, the cooling effect of clouds is larger than their warming effect. Scientists calculate that if clouds never formed in Earth s atmosphere, our planet would be over 20 C warmer on average. Conditions on Earth affect the amount and types of clouds that form overhead. This helps to shape local climate. For example, in rain forests, the trees release large amounts of water vapor. As daily heating causes the air to rise, clouds form and intense rainstorms occur. Over three quarters of the water in tropical rain forests is recycled in this way and cloud cover is almost complete for most of the year. In contrast, in a desert there is no surface source of moisture and clear conditions are typical. These clear conditions allow for more heating by sunlight and larger maximum temperatures. In both cases, the local climate precipitation and temperature is tied to cloud conditions. Human activities also can affect cloud conditions. One specific and obvious example is the formation of contrails, or condensation trails. These are the linear clouds formed when a jet aircraft passes through a portion of the atmosphere having the right combination of moisture and temperature. The jet exhaust contains some water vapor as well as small particles aerosols that provide condensation nuclei that help ice crystals begin to form. In some areas, jet traffic is causing a noticeable change in cloudiness, which may affect both weather and climate. Clouds and the Energy Cycle The study of clouds, where they occur, and their characteristics, may well be the key to understanding climate change. Low, thick clouds primarily reflect solar radiation and cool the surface of the Earth. High, thin clouds primarily transmit incoming solar radiation; at the same time, they trap some of the outgoing infrared radiation emitted by the Earth and radiate it back downward, thereby warming the surface of the Earth. Whether a given cloud will heat or cool the surface depends on several factors, including the cloud's height, its size, and the make up of the particles that form the cloud. The balance between the cooling and warming actions of clouds is very close although, overall, cooling predominates. The Earth's climate system constantly tries to maintain a balance between the energy that reaches the Earth from the sun and the energy that goes from Earth back out to space. Scientists refer to this process as Earth's "radiation budget." The components of the Earth system that are important to the radiation budget are the planet's surface, atmosphere, and clouds. The energy coming from the sun to the Earth's surface is called solar or "shortwave" energy, because most of it is in the form of the shorter wavelengths of electromagnetic radiation, which are those responsible for the CALIPSO / CloudSat February 17, 2004 Videoconference Materials 4

5 visible light detected by our eyes. Both the amount of energy and the wavelengths at which energy is emitted by any system are controlled by the average temperature of the system's radiating surfaces. The temperature of the sun's radiating surface, or photosphere, is more than 5500 degrees C (9900 degrees F). However, not all of the sun's energy comes to Earth. The sun's energy is emitted in all directions, with only a small fraction being in the direction of the Earth. Energy goes back to space from the Earth system in two ways: reflection and emission. Part of the solar energy that comes to Earth is reflected back out to space in the same, short wavelengths in which it came to Earth. The fraction of solar energy that is reflected back to space is called the albedo. Different parts of the Earth have different albedos. For example, ocean surfaces and rain forests have low albedos, which mean that they reflect only a small portion of the sun's energy. Deserts and clouds, however, have high albedos; they reflect a large portion of the sun's energy. Over the whole surface of the Earth, about 30 percent of incoming solar energy is reflected back to space. Because a cloud usually has a higher albedo than the surface beneath it, the cloud reflects more shortwave radiation back to space than the surface would in the absence of the cloud, thus leaving less solar energy available to heat the surface and atmosphere. Hence, this "cloud albedo forcing," taken by itself, tends to cause a cooling or "negative forcing" of the Earth's climate. Another part of the energy going back to space from the Earth is the electromagnetic radiation emitted by the Earth. The solar radiation absorbed by the Earth causes the planet to heat up until it is emitting as much energy back into space as it absorbs from the sun. Because the Earth is absorbing only a tiny fraction of the sun's energy, it remains cooler than the sun, and therefore emits much less radiation. Most of this radiation is at longer wavelengths than solar radiation. Unlike solar radiation, which is mostly at wavelengths visible to the human eye, the Earth's longwave radiation is mostly at infrared wavelengths, which are invisible to the human eye. When a cloud absorbs longwave radiation emitted by the Earth's surface, the cloud reemits a portion of the energy to outer space and a portion back toward the surface. The intensity of the emission from a cloud varies directly as its temperature and also depends upon several other factors, such as the cloud's thickness and the makeup of the particles that form the cloud. The top of the cloud is usually colder than the Earth's surface. Hence, if a cloud is introduced into a previously clear sky, the cold cloud top will reduce the longwave emission to space, and (disregarding the cloud albedo forcing for the moment) energy will be trapped beneath the cloud top. This trapped energy will increase the temperature of the Earth's surface and atmosphere until the longwave emission to space once again balances the incoming absorbed shortwave radiation. This process is called "cloud greenhouse forcing" and, taken by itself, tends to cause a heating or "positive forcing" of the Earth's climate. Usually, the higher a cloud is in the atmosphere, the colder is its upper surface and the greater is its cloud greenhouse forcing. If the Earth had no atmosphere, a surface temperature far below freezing would produce enough emitted radiation to balance the absorbed solar energy. But the atmosphere warms the planet and makes Earth more livable. Clear air is largely transparent to incoming shortwave solar radiation and, hence, transmits it to the Earth's surface. However, a significant fraction of the longwave radiation emitted by the surface is absorbed by the air. This heats the air and causes it to radiate energy both out to space and back toward the Earth's surface. The energy emitted back to the surface causes it to heat up more in order to emit enough radiation to balance the added amount it receives from the air. This heating effect of air on the surface, called the atmospheric greenhouse CALIPSO / CloudSat February 17, 2004 Videoconference Materials 5

6 effect, is due mainly to water vapor in the air, but also is enhanced by carbon dioxide, methane, and other infrared absorbing gases. In addition to the warming effect of clear air, clouds in the atmosphere help to moderate the Earth's temperature. The balance of the opposing cloud albedo and cloud greenhouse forcings determines whether a certain cloud type will add to the air's natural warming of the Earth's surface or produce a cooling effect. As explained below, the high thin cirrus clouds tend to enhance the heating effect, and low thick stratocumulus clouds have the opposite effect, while deep convective clouds are neutral. The overall effect of all clouds together is that the Earth's surface is cooler than it would be if the atmosphere had no clouds. High Clouds The high, thin cirrus clouds in the Earth's atmosphere act in a way similar to clear air because they are highly transparent to shortwave radiation (their cloud albedo forcing is small), but they readily absorb the outgoing longwave radiation. Like clear air, cirrus clouds absorb the Earth's radiation and then emit longwave, infrared radiation both out to space and back to the Earth's surface. Because cirrus clouds are high, and therefore cold, the energy radiated to outer space is lower than it would be without the cloud (the cloud greenhouse forcing is large). The portion of the radiation thus trapped and sent back to the Earth's surface adds to the shortwave energy from the sun and the longwave energy from the air already reaching the surface. The additional energy causes a warming of the surface and atmosphere. The overall effect of the high thin cirrus clouds then is to enhance atmospheric greenhouse warming. Low Clouds In contrast to the warming effect of the higher clouds, low stratocumulus clouds act to cool the Earth system. Because lower clouds are much thicker than high cirrus clouds, they are not as transparent: they do not let as much solar energy reach the Earth's surface. Instead, they reflect much of the solar energy back to space (their cloud albedo forcing is large). Although stratocumulus clouds also emit longwave radiation out to space and toward the Earth's surface, they are near the surface and at almost the same temperature as the surface. Thus, they radiate at nearly the same intensity as the surface and do not greatly affect the infrared radiation emitted to space (their cloud greenhouse forcing on a planetary scale is small). On the other hand, the longwave radiation emitted downward from the base of a stratocumulus cloud does tend to warm the surface and the thin layer of air in between, but the preponderant cloud albedo forcing shields the surface from enough solar radiation that the net effect of these clouds is to cool the surface. Deep Convective Clouds In contrast to both of the clouds previously discussed are deep convective clouds, typified by cumulonimbus clouds. A cumulonimbus cloud can be many kilometers thick, with a base near the Earth's surface and a top frequently reaching an altitude of 10 km (33,000 feet), and sometimes much higher. Because cumulonimbus cloud tops are high and cold, the energy radiated to outer space is lower than it would be without the cloud (the cloud greenhouse forcing is large). But because they also are very thick, they reflect much of the solar energy back to space (their cloud albedo forcing is also large); hence, with the reduced shortwave radiation to be CALIPSO / CloudSat February 17, 2004 Videoconference Materials 6

7 absorbed, there is essentially no excess radiation to be trapped. As a consequence, the cloud greenhouse and albedo forcings almost balance, and the overall effect of cumulonimbus clouds is neutral neither warming nor cooling. Cloud Key Concepts The effect of clouds on climate depends on the competition between the reflection of incoming solar radiation and the absorption of Earth's outgoing infrared radiation. Low clouds have a cooling effect because they are optically thicker and reflect much of the incoming solar radiation out to space. High thin cirrus clouds have a warming effect because they transmit most of the incoming solar radiation while, at the same time, they trap some of the Earth's infrared radiation and radiate it back to the surface. Deep convective clouds have neither a warming nor a cooling effect because their cloud greenhouse and albedo forcings, although both large, nearly cancel one another. Mission Information CALIPSO and CloudSat are two satellites scientists will use to research the atmosphere and effects on weather and climate. Both CALIPSO and CloudSat will fly in formation with the EOS Aqua and Aura satellites and the French PARASOL satellite as part of the Afternoon Constellation. The Afternoon Constellation is a group of six polar orbiting satellites that will fly in formation to allow investigations of the Earth system by synergistically combining data from multiple platforms. The Aqua satellite was launched in May The Aura satellite was launched on July 15, 2004 and the PARASOL satellite was launched on December 18, CALIPSO and CloudSat satellites are scheduled for launch in The sixth satellite is OCO, scheduled for launch in CloudSat (see GLOBE science report for additional material) First in line after the Aqua satellite which was launched in May, 2002, is CloudSat. As its name implies, CloudSat will collect data on clouds with an instrument known as a Cloud Profiling Radar (or CPR). Clouds are one of the least understood elements of climate and the hydrological cycle. Yet without an understanding of clouds, weather forecasting and climate modeling become nearly impossible. For millennia, humans have studied clouds from the ground. Over the last century, it has become possible to study clouds from above. Until now, though, there was no good way to study the insides of clouds. The A Train will make this possible, especially through the NASA CALIPSO and CloudSat missions. CALIPSO and CloudSat will use different types of remote sensing instruments for atmospheric data collection. CloudSat will use a special type of active microwave radar (94 GHz) to provide a global survey of cloud properties to aid in improving cloud models and the accuracy of weather forecasts, with the long term goal of improving global climate models (Figure 2). This cloud profiling radar (CPR) will provide vertical distribution of cloud physical properties including liquid water content, ice content, and cloud optical depth (Stephens et al., 2002). The CloudSat mission is a cooperative effort that includes its international partner, Canada, and its industry partner, Ball Aerospace and CALIPSO / CloudSat February 17, 2004 Videoconference Materials 7

8 Technologies Corporation. Among CloudSat s other partners are Colorado State University, Jet Propulsion Laboratory, Canadian Space Agency, the U.S. Air Force, U.S. Department of Energy, Goddard Space Flight Center and scientists from France, United Kingdom, Germany, Japan and Canada. The CloudSat website is: Mission Science Objectives CloudSat seeks to overcome shortcomings in the treatment of cloud processes in climate models and the lack of the observational constraints needed to accurately characterize these processes or to validate models The CloudSat Mission will provide the first global survey of the synoptic and seasonal variations of cloud vertical structure, and frequency of occurrence. It will also provide quantitative information on cloud layer thickness, base and top altitudes, cloud optical thickness, and cloud water and ice contents. These measurements are a significant advance over present observing capabilities. CloudSat primary science objectives: 1. Quantitatively evaluate the representation of clouds and cloud processes in global atmospheric circulation models, leading to improvements in both weather forecasting and climate prediction; 2. Quantitatively evaluate the relationship between the vertical profiles of cloud liquid water and ice content and the radiative heating by clouds. CloudSat secondary science objectives: 3. Improve and validate cloud information derived from other satellite systems, in particular those of EOS. 4. Improve our understanding of the indirect effect of aerosols on clouds by investigating (in cooperation with other satellite platforms) the effect of aerosols on cloud formation and cloud type NASA ESSP satellite CloudSat (courtesy of Ball Aerospace). CALIPSO / CloudSat February 17, 2004 Videoconference Materials 8

9 CALIPSO (Cloud Aerosol Lidar and Infrared Pathfinder Satellite Observations) Flying in tandem with CloudSat will be CALIPSO. In addition to gases, clouds contain liquid droplets and solid particles known as aerosols. CALIPSO stands for Cloud Aerosol Lidar and Infrared Pathfinder Satellite Observations (Figure 3). CALIPSO will use LIght Detection And Ranging (LIDAR) to provide an opportunity for more comprehensive atmospheric data collection on aerosols. Lidar uses pulses of light generated by a laser to pass through the atmosphere, where a fraction is then scattered back by aerosols and cloud particles to a receiver. The CALIPSO satellite will fly in a polar orbit to vertically profile aerosols and clouds using the first satellite lidar dedicated to atmospheric sensing (Winker et al., 2002). The lidar will observe the vertical distribution of aerosols and provide information on particle size and phase, improving our understanding of the role aerosols play in Earth s climate system. The CALIPSO mission is a cooperative effort led by NASA s Langley Research Center and includes the French Space Agency CNES, Hampton University, Ball Aerospace and Technologies Corporation, and the French Institut Pierre Simon Laplace. The CALIPSO website is: NASA satellite CALIPSO ( calipso.larc.nasa.gov/). Mission Objectives CALIPSO is currently being developed to help scientists answer significant questions and provide new information about the effects of clouds and aerosols (airborne particles) on changes in the Earth's climate. Understanding these components will provide the international science community with a more comprehensive data set that is essential for a better understanding of the Earth's climatic processes. Accurate climate model predictions will provide international and national leaders accurate information to make more informed policy decisions about global climate change. The composition of the global atmosphere has changed during this century because of human activities. Climate models now predict a significant global warming in response to the rising concentrations of carbon dioxide and other greenhouse gases in the atmosphere. However, confidence in these predictions is low because of significant uncertainties in the modeled radiative effects of aerosols (small suspended particles) and clouds. Current predictive capabilities must be improved to enable policy makers to reach balanced decisions on mitigation CALIPSO / CloudSat February 17, 2004 Videoconference Materials 9

10 strategies. CALIPSO was selected as an Earth System Science Pathfinder satellite mission in December 1998 to address the role of clouds and aerosols in the Earth's radiation budget. The CALIPSO mission is managed by NASA's Goddard Space Flight Center and implemented by NASA's Langley Research Center for the NASA Earth System Science Pathfinder (ESSP) program and collaborates with the French space agency Centre National d'etudes Spatiales (CNES), Ball Aerospace and Technologies Corporation, Hampton University and the Institut Pierre Simon Laplace in France. CALIPSO is scheduled for launch in Requisite Resources Watch NASA Connect video entitled The A Train Express Access other resources related to this program at CALIPSO / CloudSat February 17, 2004 Videoconference Materials 10

11 Lesson 1 (To be completed prior to the Video Conference) Clouds that warm Clouds that cool (Note: Much more detailed lesson plans about these topics can be found at the GLOBE website in the Educator s Corner section Objectives By the end of this lesson the student will have investigated the effects of clouds on surface temperature. Background Clouds are named according to their height, shape and color. There are low clouds (below 2 kilometers), medium clouds (2 7 kilometers) and high clouds (above 7 kilometers). There are also clouds that stretch long distances through the atmosphere. Because the air is so cold, high clouds are normally made up of tiny ice particles. Cirrus are high, white, feathery clouds. They are made up of ice crystals and don't bring rain. Clouds with a woolly appearance are called cumulus. Sometimes they are small low level clouds. They can also be present during thunderstorms, reaching heights of 15 kilometers. Cumulus clouds often produce shower. Stratus are low grey clouds. If the air is very still, tiny water droplets can fall to the ground as a drizzle. In general, high clouds warm the Earth's surface and low clouds have a cooling effect. CALIPSO / CloudSat February 17, 2004 Videoconference Materials 11

12 Student Cloud Chart (GLOBE Cloud Charts may be used if available) Cirrus: high level, white tufts or filaments; made up of ice crystals. (No precipitation.) Cirrocumulus: high level, small rippled elements; ice crystals. (No precipitation.) Cirrostratus: high level, transparent sheet or veil, halo phenomena; ice crystals. (No precipitation.) Altocumulus: middle level layered cloud, rippled elements, generally white with some shading. May produce light showers. Altostratus: middle level grey sheet, thinner layer allows sun to appear as through ground glass. Precipitation: rain or snow. Nimbostratus: thicker, darker and lower based sheet. Precipitation: heavier intensity rain or snow. Stratocumulus: low level layered cloud, series of rounded rolls, generally white. Precipitation: drizzle. Stratus: low level layer or mass, grey, uniform base; if ragged, referred to as "fractostratus". Precipitation: drizzle. Cumulus: low level, individual cells, vertical rolls or towers, flat base. Precipitation: showers of rain or snow Cumulonimbus: low level, very large cauliflower shaped towers to 16 km high, often "anvil tops". Phenomena: thunderstorms, lightning, squalls. Precipitation: showers of rain or snow CALIPSO / CloudSat February 17, 2004 Videoconference Materials 12

13 Procedures (Note: If students and teachers are familiar with GLOBE protocols, they should use them for this activity.) Use a thermometer in a shady location about a meter above the ground well away from buildings to measure the temperature on clear and cloudy days over a few days. Along with the temperature measurement, students should also note the time and date. Students should take measurements as early in the day and as late in the day as their school schedule allows. Use the cloud chart to record the type of cloud present. Estimate the fraction of the sky covered by cloud. An easy way is to observe how many eighths of the sky is cloudy. For example, if half the sky contains clouds, you would describe the cover as 4/8. If clouds occupy only a fraction of the sky, you would write 1/8. CALIPSO / CloudSat February 17, 2004 Videoconference Materials 13

14 Student Data Sheet Date Time Temperature Type of Clouds Present Fraction of Cloud Cover Student Questions 1. Examine your data to see if you can work out what influence clouds have on surface temperatures. 2. Are there some types of clouds that seem to increase surface temperatures? Which types? 3. Are there some types of clouds that seem to lower surface temperatures? Which types? CALIPSO / CloudSat February 17, 2004 Videoconference Materials 14

15 Lesson 2 (To be completed prior to the Video Conference) Warming up Land and Water Objectives: By the end of this lesson the student will: have examined how different materials absorb energy from the sun have examined how different materials effect energy absorption Equipment Safety desk lamp, reading light or 100 watt globe stand and clamp two shallow bowls or similar containers dry sand or soil two thermometers Polyester Quilt Batting, Window Screen, Flannel (quantity depends on number of groups and size of containers) Take care that you don't touch the hot light bulb. Procedure 1. Pour water to a depth of about 2 cm into one bowl. 2. Put the same depth of dry sand in the other bowl. 3. Place a thermometer in each bowl, with the bulb just below the surface. 4. Put the bowls next to each other and adjust the light bulb so that it is about 15 cm above the surface of the sand and water. CALIPSO / CloudSat February 17, 2004 Videoconference Materials 15

16 5. Record the temperature in each bowl before the lamp is turned on. 6. Turn on the lamp. Leave it on for five minutes. Record the temperature in each bowl after each minute. 7. After five minutes, turn off the lamp. Continue to read the temperature in each bowl after each minute for another five minutes. 8. Draw a graph to show how the temperature changed in each of the bowls. You can plot the temperatures in both bowls on the same graph. 9. Repeat steps 1 8 except in step 4, place a piece of metal screen big enough to cover both containers at a height of 12 cm from the surface of the sand and water. We suggest using two burner stands and clamps to suspend the material. 10. Repeat steps 1 8 except in step 4, place a piece of polyester quilt batting big enough to cover both containers at a height of 8 cm from the surface of the sand and water. We suggest using two burner stands and clamps to suspend the material. 11. Repeat steps 1 8 except in step 4, place a piece of cotton flannel big enough to cover both containers at a height of 4 cm from the surface of the sand and water. We suggest using two burner stands and clamps to suspend the material. Special Note: Keep a large bucket of water and extra sand that is at room temperature so that students materials are always at room temperature for each trial. CALIPSO / CloudSat February 17, 2004 Videoconference Materials 16

17 Student Data Sheet Trial #1 No cover between sand and water Time (minutes) Temperature of water Temperature of sand Trial #2 Metal Screen 12cm from sand and water Time (minutes) Temperature of water Temperature of sand Trial #3 Quilt Batting 8cm from sand and water Time (minutes) Temperature of water Temperature of sand CALIPSO / CloudSat February 17, 2004 Videoconference Materials 17

18 Trial #4 Cotton Flannel 4cm from sand and water Time (minutes) Temperature of water Temperature of sand Student Questions 1. What was the temperature increase during heating in the: A) Water? B) Sand? 2. How did the temperature changes in the water compare with those in the sand? 3. How did the temperature changes in the sand and water without any type of cover material compare to those during the screen, quilt batting, and flannel trials? 4. Which heats up more quickly during the day water (such as lakes or the sea) or land? Which cools more quickly when sunlight is absent land or water? CALIPSO / CloudSat February 17, 2004 Videoconference Materials 18

19 5. How does cloud cover affect the heating and cooling of the earth? 6. Use your graph to try to predict how long it would have taken the sand and the water to cool to their original temperatures. CALIPSO / CloudSat February 17, 2004 Videoconference Materials 19