It is the change to these transitions, such as the average date of first frost, that are an important key to understanding a changing climate.  Even small changes can have a large effect on migrating birds.  The date of first or last frost can prompt birds to begin their flight patterns either too early or too late, which puts their survival at risk.  The Ruby-throated Hummingbird (Archilochus colubris), for example, may be prompted to migrate later due to temperatures remaining warm late into autumn.  However, as they migrate, they may encounter colder weather due to a transitioning Arctic weather system.  If they left their summering location at their normal time, they would avoid these extreme weather events.  You can see the normal migration pattern of the Ruby-throated Hummingbird in the map below.

Image from Journey North, depicting the migratory route of the Ruby-throated Hummingbird. Finish is their wintering location in Costa Rica

This idea is further supported in the following map, which was produced by the Audubon Society and NOAA which shows that migrating birds are spending their winters farther north due to warming temperatures.  The light blue dots symbolize the general location each species wintered in 1966-1967. The dark blue dots connected by the line represent where the species wintered in 2005-2006.

Map showing changes in wintering location for various bird species from 1966-67 to 2005-06. From Audubon Society and NOAA

In some cases, these birds are more than 650 km from their 1966-1967 wintering location.  In addition to putting the birds in the path of transitioning weather patterns, dramatic shifts like these can upset the delicate balance of local ecosystems; insects and plants that these birds naturally prey on may quickly become over-populated if the migrating birds are wintering elsewhere. An example of this can be seen in the Elementary GLOBE book, “The Mystery of the Missing Hummingbirds.”

As we venture further into autumn in the Northern Hemisphere and spring in the Southern Hemisphere, it is important to keep an eye to our GLOBE instruments to monitor the changes that are affecting not only birds, but plants and other creatures that rely on weather changes for their survival.

You, as a GLOBE student, are given a unique opportunity to collect and submit data that can be used to study the transition seasons.  Students in the Kingdom of Bahrain are already examining this change in order to understand how the birds are adapting to their changing climate.   Be sure to start performing basic protocols, such as air temperature, precipitation and soil temperature, and add in other phenological protocols, such as Ruby-throated Hummingbird observations, arctic bird migration and green up or green down, to monitor these important transition season events.  And be sure to let us know about your research as it develops. These activities also help students understand the Next Generation Science Standards of Crosscutting Concepts, such as “Cause and Effect” and “Systems and System Models,” found in the progression of Earth Systems Science.

In the Kingdom of Bahrain, over 290 species of birds have been observed, the majority being passing migrants.  Monitoring migratory birds isn’t always easy, as many migratory birds fly at a great height, making them hard to see. Some birds, such as cuckoos (family: Cuculidae) and orioles (family: Oriolidae), migrate during the night.  There are others which migrate during the day, such as hoop (family: Upupidae), swallows (family: Hirundinidae), pipits and wagtails (family: Motacillidae), and larks (family: Alaudidae).

In addition to these land birds, wader birds are also observed in the Kingdom of Bahrain.  Wader birds are birds that are characterized by their long legs and like to frequent shallow waters in search of food.  These types of birds are best seen during the low tide.  The Socotra Cormorant (Phalacrocorax nigrogularis), for example, is a wader bird that is commonly found during migratory season in the Kingdom of Bahrain.

Regardless of the species of migratory bird, the area near Muhrraq and south of the airport are considered great areas for migratory bird monitoring.  Additionally, the eastern coast of the Kingdom of Bahrain, such as along the Bay of Tubli and Arad, as well as coasts of Ghalalee and  Amwaj, are other areas that many of these migratory bird species can be found.

With the wealth of bird species observed in the Kingdom of Bahrain, The GLOBE Centre for Earth Sciences and Renewable Energy, in Collaboration with the University of Bahrain scientists, has been preparing a study on wading and migratory bird overflow in the country.  This project aims to expand students’ knowledge of scientific research and introduce them to the local bird species of their environment.  Furthermore, it is anticipated that through this project and through the use of GLOBE protocols and the collection of data, students will become more environmentally aware while at the same time learning the skills necessary to perform scientific research.  Students from 13 secondary schools and 8 intermediate schools will monitor bird migration throughout the Kingdom of Bahrain and learn to work together to achieve a common goal.

To reach the goal of the project, students will identify their local migratory birds and observe how they adapt to the local environment.  The students will then statistically analyze the specific types and numbers of birds, allowing them to hone their bird classification skills.  By analyzing bird observations in addition to other GLOBE protocols, students will be able to: identify the possible effects of climate change on the environment for the migratory birds; be able to identify endangered birds and suggest ways to protect them; and come away with an understanding of the human impact on birds and how to prevent further species loss.

Suggested activity:  Have you ever considered observing when certain migratory bird species arrive and depart your area?  Phenological projects such as this from the Kingdom of Bahrain can be repeated in your local area.  Investigate migratory patterns of species you are familiar with and begin making observations of not only the arrival and departure of the birds but also environmental conditions, such as air, soil or surface temperature, budding of trees and flowers, etc.  Collecting data can help you see if there might be a connection. The GLOBE Program offers students the opportunity to collect bird migration data through the following protocols, Arctic Bird Migration and Operation Ruby Throat: The Hummingbird Project, as well as the Phenology and Climate Intensive Observing Period. 

Whenever I talk with teachers about studying phenology, their first question is always, “What is phenology?” To me, phenology is one of the most exciting observations we can make through GLOBE. The ability to observe, first hand, the life cycles of living things and how the processes change with seasons is an amazing connection to our environment. Sometimes it can be hard to visualize the potential impacts of climate change. This makes sense, because with climate we are talking about long time scales, so thinking about how our environment may be different in 30, 100 or even 1000 years from now can be difficult to understand. However, with plant phenology, you can start tracking real-life observations that may indicate how our environment is changing now.

The GLOBE Program provides some engaging protocols for phonological data collection. Scientists have been observing these changes in the environment for years using satellite images, measuring vegetation “greenness” using the Normalized Difference Vegetation Index (NDVI). Students can observe this greening of Earth through the seasons using various web-based tools at several websites.

My NASA DATA allows students to access NDVI data and create their own color plots and time series graphs of NDVI

Satellite data can be used to monitor the health of plant life from space, and is visualized through this video (click the image to open a new window with the video) . The Normalized Difference Vegetation Index (NDVI) provides a simple numerical indicator of the health of vegetation which can be used to monitoring changes in vegetation over time. This animation shows the seasonal changes in vegetation by fading between average monthly NDVI data from 2004. The loop begins on September 24 and repeats six times during one full rotation of the globe at a rate of one frame per day. The fade for each month is complete on the 15th of each month.

The GLOBE Program also provides learning activities to facilitate the understanding of the science behind this investigation. One such learning activity is Green-up Cards. Creating your own class set of Green-Up Cards is a great way to start tracking local plant phenology.  As a trainer, I have incorporated this learning activity into my workshops, but have always wanted to showcase local plant species.  Teachers see the usefulness of this activity because it uses sequencing and pattern skills and helps illustrate the importance of detailed observations.  Teachers often ask if there is a database of photos they can use to help train their students in determining the vegetative phases of plant development.  By having GLOBE students around the world make their own Green-Up Cards, we can create a library of plant photos showcasing green-up across the globe.

NASA Langley engineer David Beals has spent time looking at plant phenology and captured the following images.  These are great examples of what you can include in your Green-Up Card.

Similar cards can be created for Green-Down, exhibiting the colors of plant senescence.  Documenting your plant phenology observations through photos and sketches is a great way for students to track plants’ life cycle and it creates a resource for future student observers.  This can be a part of your Student Climate Research Campaign  activities. You can extend this activity further by comparing your plant observations to local temperature and precipitation measurements.

Suggested activity: Start gathering your equipment and define a site for documenting Green-Up if you’re in the Northern Hemisphere.  You can learn additional information about this activity on the GLOBE website.  Once you begin taking photographs or drawings, share them with us on Facebook.  You could also use this activity as an inspiration for your entry into the GLOBE Earth Day Video Competition, which is occurring right now.

Cloud Forest located in Mount Kinabalu, Borneo Photo Credit: Nep Grower

Scientists became interested in how cloud forests work after they started studying some of the amphibians and migratory birds that live in cloud forests.  For a long time, a lot was known about the animals, but not about the vegetation that provided homes for all these animals.  This inspired a group of researchers from the University of California at Berkeley to research the cloud forests of Monteverde, Costa Rica. The cloud forests in Monteverde receive precipitation about 9 months out of the year.  During the other three months, Monteverde receives very little precipitation, but it does get fog.  Some parts of the forests will have fog for an average of 13 hours per day.  This fog forms when moist air from the Caribbean Sea condenses under the forest’s canopy.

A quetzal - a bird that lives in cloud forest trees Photo Credit: Drew Fulton (Canopy in the Clouds)

In order to study where the water in the trees comes from, scientists heated a spot on their branches and then tracked how the warmed water under the spot moved.  If the water moved towards the leaves, it came from the roots.  If the water moved towards the trunk, it came from the leaves.  After studying trees both in and out of cloud forests, the scientists found that the trees in the cloud forests could store 20% more water for growth via foliar uptake than the trees outside of the cloud forests.   Scientists had long suspected that the ecology of cloud forests was tied to the fog and low-level clouds, but not until this research was conducted were they able to say that cloud forests do obtain water via the clouds.

For more information, here is a research group in Costa Rica that studies cloud forests.

Some of our GLOBE schools are near cloud forests.  We would love if you could share your pictures and experiences via email to science@globe.gov or by leaving a comment.  Also, for all our GLOBE schools – we want to wish you a Happy New Year and remind you to always keep investigating!  You might find something amazing.

-Julie Malmberg

This year, as part of the GLOBE Phenology and Climate Project, myself and other scientists at The GLOBE Program Office established a phenology site near our office building. Our colleague and GLOBE Master Trainer, Gary Randolph, trained us in how to follow the Green-Down Protocol. We found a non-irrigated tree that faced toward the equator (south since we are in the Northern Hemisphere), identified the tree as a Boxelder (scientific name of Acer negundo) using our Rocky Mountain tree finder guide, and documented the site location using a GPS.

Using the Rocky Mountain Tree Finder to identify our tree

Then, we selected four leaves on an accessible branch, including a terminal leaf and marked them by tying bright orange tape around the stems. The marking tape we utilized was actually used construction caution tape that we were “recycling” for our measurements, and we had labeled each piece with a number for each leaf.

Marking the leaves with recycled tape at the phenology site

We each took turns comparing the leaves with the GLOBE Plant Color Guide. It was not always easy to tell exactly which color the leaf was, but we matched the predominant color of the leaf and came to a consensus among our group before recording the observations. Most of the time, we were all in agreement, but when we weren’t we discussed it and came to a decision as a group. We also established a soil temperature site near the base of our tree, in which we took soil temperature measurements at 5 cm and 10 cm and the air temperature every time we did green-down observations.

Determining the color of our leaves with the GLOBE Plant Color Guide

Over the past month and a half, we went out to collect data about twice per week. At first the leaves’ color didn’t change. While this made taking the measurements less exciting at first, it was very important that we had begun early in order to make sure we captured the onset of the green-down process. Nonetheless, in the past couple weeks we realized the leaves were turning color quickly, so we started going out three times per week to capture the color changes in our data. Early this week, we arrived at our green-down site to find three of the four leaves had fallen to the ground. The one leaf that remained intact was very fragile, curled up, and lacking in color compared to what it had once been.

GLOBE Director Dr. Tony Murphy makes one of the final green-down measurements

As I looked around at the trees near our site, I was amazed at the variety of stages of green-down that the nearby trees were in. Some trees had already lost almost all of their leaves, while some still had vibrant greens and yellows on display. I wondered what causes such variation in the timing of green-down from tree-to-tree? Could it be dependent on the species of tree or the amount of sunlight it gets? Perhaps it relates more to the soil conditions and soil moisture? Or maybe it is a combination of factors together, such that maybe each species needs certain amounts of sunlight and moisture to prevent green-down from beginning? When I asked myself these questions I was exercising my curiosity about the world around me. For me, this is the essence of science: to inquire about things I don’t understand, create hypotheses while I consider the problem, and then design a process to find the answers.

As the last leaf falls and I reflect on my experience doing the Green-Down Protocol, I realize I’ve learned much more than I could have by reading about it in a book and the experience has had a much bigger impact than a typical desk assignment. The data we collected will be archived in the GLOBE database where it can be used for research. The observations of nature that I made while being outside have left a lasting impression on me, as well as energized me to keep learning more about my environment. And this was all because four special leaves beckoned us to get outside, breath some fresh air, and do science.

Suggested activity: As you take measurements with GLOBE protocols, pay attention to what is happening around your measurement sites. Do you understand all of the changes and processes that you observe? If not, design a research project to help you answer the questions that make you curious about the environment and share it with us at science@globe.gov.

-Sarah Tessendorf

Tree-of-heaven (Ailanthus altissima) is spreading widely throughout West Virginia and threatening the native forest ecosystems in Appalachia.  This invasive plant was introduced to the United States from China in the 1780s. The same exotic tree species was also introduced to Japan in 1860s but is not aggressive in this country. In Japan, particularly in the Kyushu Island, tree-of-heaven is rarely found in natural forest ecosystems but a few trees may be found growing in university campuses (i.e. Kyushu University), school premises and house backyards. Tree-of-heaven was initially introduced in the US and Japan as an ornamental plant cultivated in urban areas to combat air pollution. Similarities and differences in behavior and ecology of tree-of-heaven can be attributed to different climatic regions where they exist: cool temperate in West Virginia, USA and warm temperate in Fukuoka, Japan.

Maps showing the location of tree-of-heaven in Glenville, West Virginia and Fukuoka, Japan. The invasive plants in West Virginia are naturally growing in native forests (Photo A) while those in Fukuoka, tree-of-heaven were planted on campus of Kyushu University located in the center of Fukuoka city (Photo C) and others can be found on an experimental forest that was planted for demonstration purposes (Photo B). Although tree-of-heaven were artificially planted in Fukuoka, evidence of successful establishment with significant amount of natural regeneration (seedlings) indicates their potential to eventually encroach Japan’s native forests in the future.

Continuous encroachment of Ailanthus and its accompanied modification of the site conditions pose a great threat to the existence of native plants and to the overall productivity and stability of natural forests. The success of Ailanthus and the reduction in the occurrence of native species beneath them is most likely the result of its strong competitive abilities, particularly its allelopathy (the production of one or more biochemical that influence the growth, survival, and reproduction of other organisms), faster growth rate and abundant seed crops. It has been suggested that Ailanthus modify soil microbial communities and biogeochemical cycling in ways that can feedback to benefit them. Modification of soil chemical properties by Ailanthus trees and the release of toxins from stem, leaves, and roots are mechanisms by which they can maintain dominance in the stand. Success of Ailanthus in invading forest areas can be also attributed to its ability to exploit pulses of increased resource levels such as soil moisture and light. Low soil moisture and low light observed in pure stands of Ailanthus in Japan and West Virginia indicate its efficient light interception and water consumption capabilities. Hence, increased forest disturbances, accompanied by increased availability of sunlight, soil moisture, and nutrients could lead to more opportunities for Ailanthus to become established and invade natural forests.

Based on the preliminary analysis of our data, the leaf structure and physiological parameters measured in our study revealed unique differences in the key attributes of Ailanthus between West Virginia and Fukuoka, Japan that are associated with invasive success. Although leaf size was the same in both sites, specific leaf area, an indicator of photosynthetic capacity, was found larger in trees located in West Virginia compared to those in Fukuoka. Also, our analysis revealed that those trees in Fukuoka exhibited photoinhibition that can result to a decline in photosynthetic capacity due to high light intensity. Relative water content was lower in West Virginia than in Fukuoka that may indicate the ability of tree-of-heaven in West Virginia to sustain excessive water loss without desiccation. This translates to high photosynthesis that trees in West Virginia are able to sustain during the day. There were also leaf structural differences between the two sites with those in West Virginia exhibiting light-adapted leaf characteristics with shorter stomatal length and higher stomatal density than in Fukuoka. Stomata are microscopic pores on the leaf surface where carbon dioxide and water vapor exchange take place. The different physiological and morphological parameters indicate a more aggressive nature of tree-of-heaven in West Virginia compared to Fukuoka, Japan. Although Ailanthus spp. in Fukuoka may still be in its early stage of invasion, its successful establishment where it was originally planted and aggressive physiological characteristics showed its potential to continuously invade natural forest ecosystems of Japan. Ailanthus is rarely found in natural forest in Japan which could also be due to unique environmental factors in the warm temperate environment that control its spread such as presence of biological enemies and faster decomposition rate due to high moisture and temperature that may counteract the effect of its allelopathy.

Ailanthus seedlings planted on campus of Kyushu University, Japan

A mature Ailanthus tree and naturally growing seedlings on the campus of Kyushu University, Japan.

An Ailanthus tree that was artificially planted on a demonstration forest of Kyushu University. This experimental site is mowed on a regular basis as indicated by the absence of understory vegetation.

Natural regeneration of tree-of-heaven with plenty of light exposure on an experimental forest in Kyushu, Japan

Starting today, 1 August 2012, The GLOBE Program launches its Phenology and Climate Project!  How could you connect Budburst, Green Up and/or Green Down to an invasive plant species investigation?  We’d love to hear about it!  Leave a comment or send us an email at science@globe.gov.

What does a change like this mean to the earth as a system?

Scientists are interested in studying the connections between the different Earth processes – from how greenhouse gases are trapped in the atmosphere to biological processes occurring on land.  It is important to understand these intricate connections to attempt to paint a picture of what the climate will look like in the future . This includes the connection between weather and climate to biological processes, such as animal migration or a plant’s life cycle.  This is known as phenology, or the study of a living organism’s response to seasonal and climatic changes in the environment in which they live.  Seasonal changes include amount of precipitation, temperature, variation of the amount of sun light, and other life-controlling factors

As you may know, The GLOBE Program has a suite of phenology protocols to examine the response of native species to changes in season.  For GLOBE students and teachers familiar with phenology measurements, you may recognize this as the period between Green Up and Green Down, which are two of our protocols.  A consistent change in the length of time between Green Up and Green Down can indicate a change in climate.

While there were only two types of fruits examined in this study, rowan berries and acorns, all fruiting plants go through similar life cycles and can be related to Green Up and Green Down once the plant has reached maturity.  Once budburst and leaf growth has occurred for a given growing season, flowering will begin.  Flowering may not be easily recognized, because not all plants show with large, fragrant flowers.  For example, when the oak tree flowers, it looks something like this:

Then, either due to the wind or insects, the flowers are pollinated and begin forming fruit.  Keep in mind that just because it’s called a fruit doesn’t mean it’s actually a fruit for a human to eat, as some can be poisonous!  Once these fruits ripen, they fall off and begin to form a new plant through germination and maturation.

Fruit ripening occurs typically during a specific season due to the right combinations of conditions.  If one or more of these conditions were to change, then it can be assumed that the ripening time would shift in one direction or another.  In the case of the United Kingdom, there is a correlation between the ripening dates and April temperatures.  By having warmer surface temperatures in April, flowering is occurring sooner, and thus so is fruit ripening.  There is hesitation to say that it is directly tied to temperature, but may just be a result of more sun as well as longer and warmer summers.

The major concern with the changes of ripening dates is the effect it will have on various animals that rely on fruit ripening to lead migration or use for winter food.

How can GLOBE data help answer these types of questions?  First, it’s important to begin by taking air temperature, precipitation, and cloud measurements.  Each of these factors is important to the growing season.  Next, taking Green Up, Green Down, and Budburst measurements are also important, because it can give scientists an idea if there are shifts to the growing season as a whole.

With this particular study, only 10 years of data were used.   GLOBE, however, has been around for almost 17 years!  With such a rich history, it could provide additional information that could potentially be used to answer these questions.  And while this report was for the United Kingdom, it can easily be applied to any country or region in the world that has native, flowering plants!

If you’re a GLOBE teacher, have you used any of GLOBE’s phenology protocols?  We’d love to hear if you’ve seen any changes in your data collection over the years – please leave us a comment or email us!

-jm

The recent volcanic eruption in Iceland marked by the spectacular “curtain-of-fire” and near-complete shut-down of air travel in Europe in mid-April will probably earn a place in the history books (see pictures of the Icelandic volcano at the Washington Post.)

The Icelandic Volcano. Credit: Washington Post

Two of the most commonly cited volcanic eruptions in the climate literature are Krakatua (1883; Indonesia) and Mt. Pinatubo (1991; Philippines). The most massive explosions of Krakatua took place in August, 1883, and rank among the most violent volcanic events in recorded history. In the year following the eruption, average global temperatures reportedly fell by as much as 1.2 °C (2.2 °F). Weather patterns continued to be chaotic for years, and temperatures did not return to normal until 1888. The eruption injected an unusually large amount of sulfur dioxide gas high into the stratosphere, which was subsequently transported by high-level winds all over the planet. This led to a global increase in sulfurous acid concentration in high-level cirrus clouds and the clouds became brighter. The increase in cloud reflectivity (or albedo) meant that more incoming light from the sun than usual was reflected back to space, and as a result, the entire planet became cooler, until the suspended sulfur fell to the ground as acid precipitation.

In June 1991, the best-documented explosive volcanic event to date and the second largest volcanic eruption of the twentieth century took place on the island of Luzon in the Philippines, a mere 90 kilometers northwest of the capital city Manila. Up to 800 people were killed and 100,000 became homeless following the Mount Pinatubo eruption, which climaxed with nine hours of eruption on June 15, 1991. On June 15, millions of tons of sulfur dioxide were discharged into the atmosphere, resulting in a decrease in the temperature worldwide over the next few years.

Pinatubo eruption provided scientists with a basis for constructing or modeling the change in Earth’s radiation balance (scientists like to call this change “radiative forcing”) due to explosive volcanoes. It is now well established that volcanic eruptions cause the stratosphere to warm and the annual mean surface and tropospheric temperature decreases during a period of two to three years following a major volcanic eruption. If you are interested in more technical details on how volcanoes affect climate, you can read a very good paper written by Alan Robock. Given that the Icelandic eruption is along a Mid-Ocean ridge and volcanic Hot spot, do you think the gases and aerosols will be of different composition than the Krakatoa and Pinatubo eruptions, which are associated with plate subduction along convergent plate boundaries? If there is a difference, what effect might that have on weather and climate over the next few years?

So the disruption of the air travel by the Iceland’s Eyjafjallajökull Volcanic eruptions is just the beginning; other weather and climatic effects will follow.  In the days and months ahead, we are likely to experience darkened sky and spectacular sunsets in different parts of the world.

In my last blog on birding, I took a picture of a blind on Saturday, 6 December (Figure 1). Early that morning, the temperature was cold (about -5 degrees Celsius) and the ground had about 12 centimeters of snow on the ground. The lakes near the blind were frozen when we arrived there around 9:30 a.m. local time. The temperature was probably still below freezing when I took the picture. The next morning, we woke up to 10 degree Celsius temperatures, and the 12 centimeters of snow we had in our yard had entirely disappeared. When we returned to the blind to record the how different things looked, it was 11:30 a.m. local time – about 26 hours later.

Figure 1. Picture of blind taken for last blog. Sawhill Ponds, Boulder, Colorado, 10:00 a.m. Local time. The snow was about 10 centimeters deep here; the lakes were frozen.

Figure 2. Picture of blind, roughly 26 hours later (11:30 Local Time, 7 December 2008). Note that not only has the snow disappeared, but the soil is dry in some places.

Basically the temperature didn’t fall much the night of 6 December – in fact it might have even warmed. This is because air is coming down from higher up in a Chinook. As air sinks in the atmosphere, it gets compressed (squashed) by having more air above it pressing down. This squashing warms the temperature – much as the temperature of the air in your bicycle tire warms when you pump (squeeze) more air into it. In sinking dry air, the temperature rises 10 degrees Celsius for each kilometer – quite a bit.

Figure 3 shows the temperature record for another Chinook (the instruments at NCAR Foothills Lab, which lies between where we live and Sawhill Ponds) weren’t working on 6-7 December, so I couldn’t get the data). The air is very dry during the Chinook. (The air is dry if the temperature is much higher than the dew point. Recall that fog or dew forms when the temperature and dew point are equal, so it makes sense that drier air has lower dew points). The dryness of the air is not surprising – the air is drier higher up. So the dryness is a sign that the air is coming from higher up.

Figure 3. Temperature and dew point from a Chinook on 11 February 2008, at roof level. From NCAR Foothills Laboratory in Boulder, Colorado. You can tell from the cooler temperatures starting around 15:00 local time that the Chinook ended about that time. From http://www.rap.ucar.edu/weather/.

You notice how the temperature went up half way between 23:40 (11:40 p.m.) and 02:40 (2:40 a.m.) local time and then didn’t change much for the rest of the night like it normally does? Also the temperature wasn’t going up much the next morning. (Note: 50 degrees Fahrenheit is about 10 degrees Celsius). During this time the wind was out of the west – from the mountains, meaning sinking air (Figure 4). Also notice that the temperature cools off when the wind changes from west to north at around 15:00 local time (3:00 p.m.).

Figure 4. As in Figure 3, but for wind direction

The lack of a temperature change makes me think that the air in Boulder didn’t just simply slide down the mountain, but we were getting air from above the surface. Air high above the ground doesn’t cool or warm as much as air right next to the ground does.

So we have four clues that the air came from higher up during the Chinook. First, the temperature rose to abnormally high levels at the onset of the Chinook and rapidly cooled afterward. Second, the wind came from the mountains to the west. Third, the air was very dry. And finally, the temperature didn’t change during the day like it normally does. The last clue also suggests the air came from above the surface.

What do the clouds look like? In a Chinook, the wind blowing across the mountains flows in ripples much like the water flows over rocks in a stream. It’s harder to see air flow than to see the water flow. However, clouds occur when the air is at the top of ripples, if the air is moist enough. From the surface here in Boulder, we saw a long line of low clouds stretching along the mountains (one ripple), and higher cloud doing the same thing, but farther east (Figure 5).

Figure 5. Clouds associated with the Chinook at 14:50 local time, looking northwest. The mountains are to the west. The cumulus clouds near the horizon are just to the east of the mountains, which are not visible on this picture. The higher clouds (altocumulus) are part of a broad north-south band starting east of the mountains. The little tail in the middle is the leftovers from a contrail. Looking eastward, I could see that the altocumulus clouds stretched to the horizon.

You can probably see this more clearly from space. First, I show you the visible image (Figure 6). You can see some ripples over the mountains, a dark area stretching from Boulder (plus sign) to the south, and the altocumulus (or higher) clouds extending east-south east from the dark area.

Figure 6. GOES satellite visible image of clouds at 2132 UTC (1432 Local Standard Time). The plus sign snows where Boulder is. Note the north-south clouds along the Rockies in the middle of Colorado (like ripples in the water). Then there is a broad band of clouds stretching eastward to the east side of Colorado. This is the larger-scale view of the altocumulus in Figure 5. From http://www.rap.ucar.edu/weather/satellite/.

We can see the difference in the heights of the “ripples” and the broad area of altocumulus clouds by looking at the image showing the infrared signal (Figure 7), which is related to the temperature the satellite “sees” – either at the surface or at the top of the clouds. Since the temperature in the atmosphere drops with height at these heights, this temperature can be used to estimate cloud top height. The brighter areas indicate higher cloud tops, so the broad band of clouds to the east of Boulder appear to be higher than the ripples, which are hard to see.

Figure 7. GOES satellite infrared image in and around Colorado at 2132 UTC (1432 local time). The plus sign shows where Boulder is. The broad bands of clouds are showing up much more than the ripples. Since lighter colors indicate higher clouds, this tells us that the broad area of clouds to the east is higher than the ripples – just as in the picture I took in Boulder. (But I’m not sure we can see the ripple in my picture on the satellite). From http://www.rap.ucar.edu/weather/satellite/.

What was the result of the Chinook? We already pointed out the much warmer temperatures, the complete melting of our snow (12 cm in our yard originally), and the melting of ice on many of the lakes.

This also affected the ducks in the lakes near the blind.

On 6 December, when we went out to photograph the blind, we could find no ducks on the frozen ponds – only Canada geese waddling on the ice. Also, there were almost no birds at the feeders in our back yard. We were surprised, because we thought they would be hungry in the cold weather.

On 7 December, when we got up, the feeders were full of birds. So were the trees: chickadees, pine siskins, sparrows, finches, juncos, and collared doves, were eating continuously, even when squirrels and cats (and in one case a deer with antlers) came by. Today, when we went back to Walden Ponds (north of the blind), we saw many ducks on the one pond that had thawed out most completely. And the ducks and geese were eating. My guess is that they were making up for yesterday. But – there is a mystery. Where were the ducks during the cold weather? What do you think?

Do you have names for winds where you live? Winds – particularly those that bring different weather – have names around the world. In Africa, the hot dry winds that come south from the Sahara are called Harmattans. In southern Europe, cold winds that come out of the mountains are called Boras and warm winds that come out of the mountains are called Foehns in Germany. However, we also use the word “foehn” to describe warm dry winds from the mountains in the United States. In South Africa, the warm winds coming from the mountains are called “berg winds,” since “berg” means mountain in Afrikaans. There is no snow to melt, but the berg winds do raise the temperature in winter.

Today I am blogging from San Francisco, California. I am attending the American Geophysical Union (AGU) meeting in San Francisco, California. It is a meeting that I try to come to every year. AGU is a professional organization made up of scientists who study the Earth and our solar system.

A conference like this one is a way for scientists to share information. The picture below shows how the scientists show each other the research they have performed. You might be thinking, “Dr. C, that looks a lot like a science fair that my school has.” You would be right. Poster presentations are very similar to science fair projects that students do.

Figure 1. Poster session at the AGU meeting.

Coming to the AGU meeting gives me a chance to see my scientist friends. My friend Claudia Alexander is the lead scientist on the Casini-Huygen project and Rosetta mission for NASA. The Casini-Huygen project is a satellite that is studying Saturn and its moon Titan. The Rosetta mission is going to study what makes up comets.

I presented a poster on an Earth System Science education course that I teach. Teachers take the course to continue their learning. You may have not known that either. Below is a picture of Gary Popiolkowski. He is a seventh and eighth grade science teacher at Chartiers-Houston Jr./Sr. High School in Houston, Pennsylvania. His students made the poster for him. It is a great poster as you can see from the picture. He mentioned to me how proud he was of his students for designing and making the poster.

Figure 2. Teacher Gary Popiolkowski

Figure 3. It’s me, Dr. C in front of my poster at AGU.

Dr. C