Maintenance Alert!

The MY NASA DATA lesson tables and tools will be unavailable on April 30, 2014 between 10am-4pm EDT. Please plan accordingly. If you have any questions please use the contact form to get in touch with us.

Translate MND

Dust Storms


Science Project:  Dust Storms

Image courtesy Forrest M. Mims III
Web Id: P9
Purpose: Dust storms can begin anywhere the wind blows and there is exposed soil or sand. Wind can blow the dust across a football field–or an entire ocean! You can use a camera to photograph local dust storms and the effects on the sky of major ones. You can use dust forecasts and satellite images to track major dust storms and even predict where they are headed.
Age Range: 11 to adult
Time Required: You can record a local dust event in the time it takes to make a few photographs of it. If you want to study a giant dust storm traveling across the ocean toward the United States, you can track it once a day in a 5-10 minute Internet session.
Background:

A gust of wind can launch grains of dry sand and soil into the air. These dust particles are much heavier than air, and they usually fall back to the surface after traveling a few tens of meters. However, a sustained wind may keep dust particles in the air for more than a week. The dust can rise thousands of meters in the sky and travel across oceans!

While dust storms occur around the world, some of the biggest arise in North Africa’s Sahara desert and in the Gobi desert of China and Mongolia. Depending on the time of year, dust from the Sahara desert may blow toward the Middle East, Europe, or North or South America. Sahara dust often arrives in the southern U.S. in late summer. It can reduce visibility in Florida and Texas.

African dust is blamed for incidence of asthma in Barbados. It is also blamed for carrying fungi that may damage coral. The dust is not all bad, for it provides iron for phytoplankton in the Atlantic Ocean and plants growing in tropical regions of South and Central America.

During spring, dust from the Gobi desert can blow all the way across the Pacific Ocean, where sometimes it coats car windshields with a yellowish layer of dust. Some years the dust reduces visibility across the Western U.S. But this is a mere nuisance compared to the problems it causes in China, Mongolia, Korea and Japan. For example, on bad dust days in Beijing, residents often wear dust masks to keep from inhaling the dust that fills the air.

Local and regional dust storms are common in the U.S. and Mexico. They often arise from farm fields that are barren during winter or when there is drought. They also arise in deserts across the Southwestern U.S. and Mexico.

Hawaii’s Mauna Loa Observatory, one of the world’s most important meteorological stations, has its origin in a dust storm across southern New Mexico. In June 1955 physicist Ralph Stair was frustrated by his inability to properly measure sunlight during a dust storm that blocked the sky over Sunspot in the Sacramento Mountains. Weather Bureau scientist Robert Simpson was visiting Sunspot on vacation with his teenaged daughters, Peggy and Lynn. Dr. Simpson suggested that Stair should move his experiment to Hawaii’s giant Mauna Loa mountain, where the sky is clean and clear. Simpson and Stair worked together to begin the Mauna Loa Observatory.

The Mauna Loa Observatory (MLO) is at an elevation of 3,400 meters (11.200 feet) on the north slope of Mauna Loa. Ironically, even MLO is affected by dust storms! During spring, dust from the Gobi desert often passes over MLO, where it forms clearly visible layers in the sky. Sometimes the dust layers are at the same elevation as MLO, and the dust is captured on special air sampling filters.

Significance:

While blowing dust is usually just a nuisance, major dust storms can be a health hazard. Dust may be accompanied by bacteria, fungi, pollen, pesticides, animal waste, and hazardous heavy metals like mercury and lead. Blowing dust can irritate your eyes and lungs and cause respiratory infections and asthma attacks. It can clog up engines and air filters. Intense local dust storms can reduce visibility to a few meters or less and stop traffic. Strong winds during dry seasons can blow valuable soil from farms and ranches. Because dust absorbs and reflects sunlight, it can cause a reduction in temperature. Dust might even reduce rainfall.

Project Links:
Real Time Data Source:

MODIS Rapid Response
MY NASA DATA Source:

Aerosol Data
Project Ideas:

1. People and Dust. You cause micro dust storms when you walk across dry soil on a windy day. Much more dust is produced at building and highway construction sites, rock quarries and when buildings are demolished to make room for new structures. In cities, dust sweeping machines sometimes leaves clouds of dust behind them. In the country, tractors, harvesting equipment and trucks and cars driving on unpaved roads throw considerable dust into the air, especially on windy days. You can make a photo album of people and dust. If you have access to a movie camera, you can even make a mini-documentary of people and dust. People who see your album or video will be surprised by how much dust people produce.

2. Dust Devils. Whirlwinds can occur over farm fields and even in cities and towns. When they pass over dry soil, they are known as dust devils. These are among nature’s most compact dust storms. They are very common on hot summer days in the American Southwest. They even occur on Mars! If you live in an area with dust devils, you can do a study to learn when and where they are most likely to occur. This works best if you have access to a window during the day or if you can be outdoors when dust devils are likely. An ideal study would be a map of your area that shows the approximate track of dust devils that occur on various days. This will allow you to determine the best conditions for dust devil formation. You can make photographs and videos of dust devils to record their diameter, height and speed across the landscape. Caution: Use great care if you allow a dust devil to pass over you. What might have seemed like a fun experience could pepper you with stinging gravel and even throw you to the ground. If you’re in a car, the paint might be damaged by the blowing dust. Digital cameras can also be damaged by blowing dust.

3. Sampling Dust. Have you ever noticed that dust sometimes appears on car windshields and windows? The dust sticks to the glass and doesn’t fall off, a phenomenon known as Van der Waals force. You can make use of this principle to collect dust on plastic or glass microscope slides. Find a convenient place outdoors, preferably over a grassy or paved area with little or no traffic or pedestrian traffic. Place a microscope slide at a place where it is unlikely to be noticed and where it will not fall to the ground. After a day, carefully retrieve the slide and place clear adhesive tape over it to preserve the dust you have collected. Use a microscope with a power of X100 or more to examine the particles. (Do this by looking through the glass and not the tape.) You will see many different particles, including soil dust, particles of soot (black carbon), insect and plant fragments and probably some fungal spores. The particles will range in size from less than a micrometer across to perhaps 100 micrometers. (A human hair is from about 60 to 80 micrometers in diameter.) In the spring and fall you will probably also see some pollen grains. You can use various web resources to help you identify what you find. Dust particles can have many shapes and sizes. Black particles are probably soot (black carbon). Salt crystals may be very common near the ocean. They are clear and often square in shape. Fungal spores and pollen are usually regular or symmetrical in appearance. The Fifth Kingdom is an excellent site for identifying fungal spores, but even this site does not show all of the many different kinds of spores. Many web sites are devoted to pollen identification, for example, the Pollen as Indicators of Source Areas and Foraging Resources web site.

4. Dusty Twilights. Dusty skies can cause deep red sunrises and sunsets and colorful twilight glows. Photography is the best way to record and study these events. For best results, photograph the sky over the horizon just after the sun sets. After about 20 minutes or so, the sky over where the sun set will begin to noticeably brighten if the sky is dusty. If clouds are present, they will become pink, orange or even crimson. Be sure to photograph any colorful clouds. You can place your photos in an album or a web site along with the dates and times they were made. You can use the ideas that follow to learn the origin of the sun in your photos.

5. Tracking Dust by Forecasts. The best way to find about giant dust storms is to become familiar with a web site operated by the U.S. Navy Research Laboratory (NRL). This site is the NRL/Monterey Aerosol Page, and it provides forecasts for dust, smoke and sulfate air pollution such as that emitted by coal burning power plants. The forecasts are in the form of maps that show dust, smoke and haze as color-coded patterns. To use this site, scroll down to the second box of selections under ‘Aerosol Modeling.’ Across the top are various geographical regions around the world, including World, NoAm (North America), WestUS (Western US) and EastUS (Eastern US). The far left column provides various choices. For example, ‘NAAPS Forecast Loop’ will provide a movie-like sequence of forecast images for the next several days. ‘NAAPS Current’ will provide the current forecast image. Each forecast image consists of four maps. When you select WestUS and EastUS, the upper left map shows dust in green or yellow and smoke in blue. The lower left map shows the amount of dust expected to fall to the ground. After you become familiar with this terrific site, you will be able to watch forecasts for dust as it travels across the US or even from Africa or China to the North America! Remember that the images are not satellite photos. They are forecasts. While the forecasts are reasonably accurate, they are advance predictions that may not pan out as expected. You can even study past dust events by selecting the NAAPS Archive option. The forecast maps are archived by year-month, as in 200701 (2007 January). If you select the archive for North America and click on 200701, you’ll see a column of dates and times like this:

2007013118_globaer_ops_noramer.gif (49097) View Archive Loop
2007013112_globaer_ops_noramer.gif (49064) View Archive Loop
2007013106_globaer_ops_noramer.gif (49133) View Archive Loop
2007013100_globaer_ops_noramer.gif (49170) View Archive Loop
2007013018_globaer_ops_noramer.gif (48999) View Archive Loop
2007013012_globaer_ops_noramer.gif (49020) View Archive Loop
2007013006_globaer_ops_noramer.gif (48972) View Archive Loop

There are four forecast images for each day, and each row is a forecast image coded with the date and time. For example, the file name for the image
2007013018_globaer_ops_noramer.gif (48999) View Archive Loop
indicates this date and time: 2007 (year) 01 (January) 30 (day) 18 (1800 hours UTC or Universal Time).

Universal standard time for the four continental US time zones is:

Eastern: UTC – 5 hours
Central: UTC – 6 hours
Mountain: UTC – 7 hours
Pacific: UTC – 8 hours

All this seems complicated at first, but it’s easily mastered. Be sure to look around the Navy aerosol forecast web site. There are neat satellite images and various other kinds of data.

7. Tracking Dust by Satellite. Several satellites provide images that show dust and smoke. Because these images do not necessarily distinguish between dust and smoke, it’s helpful to use satellite images in conjunction with NAQAPS forecasts described in the previous project idea. Perhaps the simplest satellite site is NASA’s web page for the OMI instrument on the Aura satellite. Click on this site and you will see two images for OMI Ozone and OMI Aerosols. The aerosol image shows dust and smoke as color coded regions on a map of the world. Colored Patterns originating from North Africa are dust and those originating from sub-Sahara Africa are smoke. Colored blobs originating in South and Central America and Southeast Asia are smoke. Those originating in the Gobi desert are dust. An ideal satellite project would compare NAAPS forecast images with satellite photos or a major dust event arriving over YOUR hometown! Even better would be to collect some dust and study it with a microscope. Sarah Mims did all this for Sahara dust arriving in Texas and won major science fair awards. Click below for two articles about these awards.

NASA Earth Observatory

Note: Mention of commercial products does not imply that they are endorsed by NASA.
Questions:

1. What do dust clouds contain in addition to dust?

2. What are some health effects of dust storms?

3. Name two major deserts that produce some of the world’s greatest dust storms.

4. Can a dust storm cross the pacific Ocean?

5. Can dusty skies cause colorful sunsets and twilights?
Going Further:

Climate change can cause major changes in rainfall that can cause deserts to expand or contract around the world. In particular, a warming climate is expected to expand deserts and this increases the likelihood and the magnitude of major dust storms.

If you want to seriously study dust storms and the effect of dust on sunlight, consider using a sun photometer to measure the dust in the sky. A sun photometer is an instrument that measures the reduction of sunlight caused by dust, smoke and air pollution in the sky. You can find out more by participating in the GLOBE aerosol program.

The web has many sites that show dust and dust storms. Some sites show magnified views of dust particles. Enter ‘dust’ in a search window to find these sites.

Project ideas contributed by Forrest M. Mims III