On 7 December, when I wrote the blog below, we were experiencing a warm wind called a “Chinook” here in Boulder, Colorado. I wanted to wait until after the surface temperature field campaign to post this. It seems appropriate to do so this morning (30 December), since we are again experiencing a Chinook, and this blog was designed to follow the second birding blog. Winds have gusted to over 100 kilometers per hour, and the temperature outside is 12 degrees Celsius – quite warm for an early morning in December! During a Chinook, the temperature warms rapidly. Chinooks are also called “snow eaters” because they can make winter snows disappear quickly. They can also make the temperature rise suddenly by tens of degrees.

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.

By taking your measurements for Dr. C., you are participating in science. Lots of scientists take measurements of different kinds to test new ideas, or to figure out how to measure things in new ways, like, for example, using a satellite instead of taking measurements everywhere on the ground. (You need to compare the new measurement with an old one that you trust.). Scientists analyze the data, and then they present the results at conferences like the one described below, and write articles about the results in scientific journals. When scientists write articles, the journals send the papers to other scientists for their opinions and suggestions before the article is ever published. These comments, and the comments from colleagues at conferences like this one for American Geophysical Union, helps scientists refine their ideas and present them more clearly to others. Also important are chance (or arranged) meetings with other scientists in the halls, next to a poster, or over coffee. Lots of fun and important ideas are exchanged at such conferences, and scientists can come away with totally new ideas about what to do next. — PL

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

This is the start of the last week of the surface temperature field campaign.

Wow, the weather around the Northern Hemisphere sure has been active. It looks like in the United States we are going to have a good old-fashioned winter with cold temperatures and stormy conditions.

Can you tell that I like winter?

I started to take an interest in weather when I was 10 years old growing up in a suburb of Buffalo, NY. Buffalo is at the eastern end of Lake Erie. The area receives significant snowfall each year called lake-effect snow. This is caused by cold air from Canada passing over the warm water in fall and winter. The air collects water vapor from Lake Erie as it crosses the lake and deposits in on the downwind side. In 1977, there was an incredible blizzard in Buffalo called the Blizzard of ‘77. School was cancelled for 5 days straight. I thought it was the best thing going. Funny, though, that my love of missing school has turned into a love for winter weather and led to my career as a professor.

Here is a recap of what has happened over the last week. There has been flooding in Hawaii as well as in Italy.

Figure 1. Location of Buffalo (New York) and Toledo (Ohio) on map of the United States.

New England Ice Storm
New England received a terrible ice storm. The storm slowly moved up the east coast of the United States and produced up to an inch of ice on tree limbs and power lines. Many trees were damaged and power lines were brought down, knocking out electricity to over a million people.
Rare snow in Texas and Louisiana
The same system that caused the ice storm produced measurable snow as far south as Houston, Texas and Lake Charles, Louisiana. See the snow cover map below to see where the snowfall occurred. Kids had a lot of fun making snowmen and throwing snow balls.

Figure 2. Snow depth map for 12 December 2008.

Blizzard in Montana, North Dakota, South Dakota and Minnesota
The weather pattern has changed dramatically. When the ice storm occurred, there was cold air and storminess in the eastern United States. The western United States was warm and calm. That has now changed. A significant winter storm has moved into the western United States. This has given much needed snow and rain to Washington, Oregon and California. This system has been accompanied by extreme cold temperatures in the Canadian plains and northern United States. High temperatures were in the –15º C range. That’s cold by anybody’s standard. The strong high pressure system in Canada that brought the cold air along with the storm system (low pressure system) produced very strong winds in Montana, North Dakota and South Dakota. This produced dangerous conditions, white-out snow conditions, drifting snow and dangerous wind chills. I have experienced four real blizzards in my lifetime. To be a blizzard, the wind speed has to be greater than 35 mph (16 m/s), visibility has to be below a ¼ mile (0.4 km), and temperatures have to be cold for three hours straight. The blizzard of ’77 in Buffalo was by far the worst blizzard I was ever in. Blizzard conditions lasted for three days straight.

Cold temperatures in Toledo, Ohio produced early ice
Where I live near Toledo, Ohio, most of November and thus far in December have been colder than the long-term average. In fact, so far in December, temperatures have averaged 4º C (7º F) below the long-term average. Ice has formed on ponds, lakes and rivers. My students and I are studying the Ottawa River that flows through the University of Toledo campus. We are doing this as part of GLOBE’s Seasons and Biomes Project. We are studying the way in which the river freezes and thaws. The observations were taken from a foot bridge and an attempt was made to keep the same part of the river in the frame. You can see in the images below that the river was ice free on 3 December 2008. By 8 December 2008, ice extended out from the banks of the Ottawa River about 4/10 of the way out on both sides of the river. There was a small area of open water down the middle of the river. Lastly, the ice started to melt on 9 December 2008 and then was completely gone by 10 December 2008 when there was quite a bit of rain. This week-long freeze up and thaw down pattern is common in Toledo, Ohio due to the changeable weather.

Figure 3. Ice on the Ottawa River, Toledo, Ohio, 3 December 2008

Figure 4. Ottawa River, 8 December 2008.

Figure 5. Ottawa River, 9 December 2008.

Figure 6. Ottawa River, 10 December 2008.

Here are schools that have entered data so far in the field campaign:
There have been 592 observations from 40 schools now recorded for the surface temperature field campaign. John Marshall High School in Glendale, WV has the most by far with 80 observations. Thanks Mrs. Clark, GO Monarchs! Peebles High School in Peebles, Ohio has logged 56 observations, thanks Mrs. Sheppard, and Dalton High School in Dalton, Ohio has reported 54, Thanks Mr. Witmer. And, thank you to all of the students from these schools.

Roswell Kent Middle School, Akron, OH, US [26 rows]
Dalton High School, Dalton, OH, US [54 rows]
Chartiers-Houston Jr./Sr. High School, Houston, PA, US [2 rows]
Lakewood Middle School, Hebron, OH, US [3 rows]
The Morton Arboretum Youth Education Dept., Lisle, IL, US [3 rows]
Peebles High School, Peebles, OH, US [56 rows]
Gimnazjum No 7 Jana III Sobieskiego, Rzeszow, PL [13 rows]
Penta Career Center, Perrysburg, OH, US [6 rows]
Canaan Middle School, Plain City, OH, US [20 rows]
Mill Creek Middle School, Comstock Park, MI, US [10 rows]
Brazil High, Brazil Village, TT [15 rows]
Kilingi-Nomme Gymnasium, Parnumaa, EE [16 rows]
Swift Creek Middle School, Tallahassee, FL, US [12 rows]
National Presbyterian School, Washington, DC, US [3 rows]
The Bryan Center, Bryan, OH, US [3 rows]
Maumee High School, Maumee, OH, US [12 rows]
Whittier Elementary School, Toledo, OH, US [4 rows]
Huntington High School, Huntington, WV, US [8 rows]
St. Joseph School, Sylvania, OH, US
Warrensville Heights High School, Warrensville Heights, OH, US [2 rows]
WayPoint Academy, Muskegon, MI, US
Gimnazium No 1, Sochaczew, PL [17 rows]
St. Michael Parish School, Wheeling, WV, US [4 rows]
Anthony Wayne High School, Whitehouse, OH, US [4 rows]
Bellefontaine High School, Bellefontaine, OH, US [20 rows]
Oak Glen High School, New Cumberland, WV, US [12 rows]
Nordonia Middle School, Northfield, OH, US [11 rows]
Orrville High School, Orrville, OH, US [6 rows]
Bowling Green Christian Academy, Bowling Green, OH, US [23 rows]
Polly Fox Academy, Toledo, OH, US [10 rows]
McTigue Middle School, Toledo, OH, US [3 rows]
Highlands Elementary School, Naperville, IL, US [8 rows]
South Suburban Montessori School, Brecksville, OH, US [20 rows]
NASA IV&V Educator Resource Center, Fairmont, WV, US
John Marshall High School, Glendale, WV, US [80 rows]
Birchwood School, Cleveland, OH, US [21 rows]
Orange Elementary School, Waterloo, IA, US
Hudsonville High School, Hudsonville, MI, US [19 rows]
The University of Toledo, Toledo, OH, US [25 rows]
Main Street School, Norwalk, OH, US [37 rows]

Dr. C

For years, I have been measuring the rain in our back yard using a standard rain gauge similar to the ones used by the U.S. National Weather Service (Figure 1). Like the gauge used by GLOBE students, rain goes through a funnel into a tube whose horizontal cross-sectional area is one-tenth that of the outer gauge, so that the measured rain is ten times the actual amount of rainfall. This year, I took a GLOBE-approved plastic gauge home. We put this one on a fence along the east side of our yard (Figure 2).

Figure 1. Rain gauge used for observations in my backyard. Normally, there is a funnel and small tube inside, but it doesn’t fit very well, so we pour the rain into the small tube after each rain event. This gauge is similar to those used by the U.S. National Weather Service. This gauge is about 25 cm in diameter.

Figure 2. Plastic raingauge matching GLOBE specs. This gauge is about 12 cm in diameter. Note the tall tree in the background.

Neither gauge is in an ideal location. In both cases, there are nearby trees (Fig. 2, map) which might impact the measuring of the rain. This is a problem a lot of schools have: there is just no ideal place to put a rain gauge. We were particularly worried about the plastic gauge, which was closer to trees than the metal gauge.

Why do we have two gauges? The metal gauge was hard to use: its funnel didn’t fit easily into the gauge, so we had to pour the rain from the large gauge into the small tube after every rainfall event. We got the plastic gauge to replace the metal one. We put the gauge on the fence because it was well-secured. But the first six months we used the new gauge, the rainfall seemed too low compared to totals in other parts of Boulder. So, I put the metal gauge back outside and started comparing rainfall data.

Figure 3. Map of our backyard. Left to right (west to east), the yard is about 22 meters across. The brown rectangular shape is our house; the circles represent trees and bushes. The numbers denote the height of the trees and bushes. The 10-m tree is an evergreen; the remaining trees and bushes are deciduous. The southeast corner of the house is about 3 m high.

How did the gauges compare?

Starting this summer, I started taking data from both gauges. Unfortunately, it didn’t rain much. And sometimes, we were away from home: so this is not a complete record. But I don’t need a complete record to compare the rain gauges.

Table: Rain measurements from the two rain gauges

The results (in the table, also plotted in Figure 4) look pretty good. With the exception of the one “wild” point on 6 October 2008, the measurements are close to one another. We think that the plastic gauge was filled when the garden or lawn next door was watered. This would not be surprising: we have found rain in the plastic gauge when there was no rain at all.

I learned after writing this blog that Nolan Doeskin of CoCoRaHS (www.cocorahs.org) has compared these two types of gauges for 12 years, finding that the plastic gauge measures slightly more rain (1 cm out of 38 cm per year, or about 2.6%).

Figure 4. Comparison of rainfall from the two rain gauges in our back yard. Points fall on the diagonal line for perfect agreement.

I learned two things from this exercise.

First, I probably should have used the two gauges before I stopped using the metal one. That way, my rainfall record wouldn’t be interrupted if the new gauge was totally wrong. (I was worried that the trees were keeping some rain from falling into the gauge. This would have led to the plastic gauge having less rainfall than the metal gauge. And, since the blockage by the trees would depend on wind direction and time of year, I wouldn’t have been able to simply add a correction to the readings.) Fortunately, the new and old gauges agreed.

In the same way, if you want to replace an old thermometer with a new one, it’s good to take measurements with both for awhile, preferably in the same shelter. Suppose the new thermometer gives higher temperatures than the old one. If you want to know the temperature trend, you can correct the temperatures for one of the two so that the readings are consistent.

The second thing I learned is that it is o.k. to reject data if there is a good reason (such as people watering their lawns). It’s also important to note things going wrong – like my spilling a little bit of water on 15 August. If you keep track of things going slightly wrong (or neighbors watering the lawn), you can often figure out why numbers don’t fit the pattern.

I will continue to compare records for awhile, to see whether the readings are close to one another on windy days. If they continue to be similar, I will be able to try a method to keep birds away from the rain gauge that was developed by a GLOBE teacher – Sister Shirley Boucher in Alabama. Keep posted!

I try to write this blog to inform, rather than to express opinion, but I have to admit that I love the metric system. Perhaps it’s because I still remember how hard it was to learn how to convert things from one set of units to another in the British system we still follow here in the United States. Ounces to pounds, feet to yards to rods, square feet to square yards to acres. And so on. While in the metric system, it’s often simply a question of multiplying or dividing by 10, 100, and so on.

So, when my children were little, I taught them to think in metric, at least for some units. I succeeded with centimeters and inches, but kilometers and miles were harder, and temperature was the hardest of all. So today I’m writing about temperature.

In using the two sets of units, it’s useful to have some mileposts (kilometer-posts?). For example:

• 0 degrees Celsius (or 32 degrees Fahrenheit), the temperature at which water freezes

and

• 100 degrees Celsius (or 212 degrees Fahrenheit), the temperature at which water boils at sea-level pressure (about 1013 millibars).

But there are some other “kilometer-posts:”

• – 40 degrees Celsius, where Fahrenheit and Celsius degrees are the same

And human body temperature:

• 37 degrees Celsius or around 98.6 degrees Fahrenheit.

And “comfortable” room temperature:

• 20 degrees Celsius or 68 degrees Fahrenheit

And, my favorite one:

• 10 degrees Celsius (or 50 degrees Fahrenheit), above which insects become active.

Since this my favorite milepost and this might not be familiar to you, I’ll fill you in on some details.

When I did my cricket blog, I couldn’t get any data points below about 10 degrees Celsius, because the crickets weren’t chirping. You can see this from the graph in Figure 1. Well, that’s not quite true. The thermometer temperature showed below 10 degrees Celsius when I heard crickets once, but the cricket was “reporting” a temperature above 10 degrees Celsius with his chirps. Not really surprising — the temperature varies a lot from place to place at night, when you hear crickets chirp. In fact, before dawn on 6 October 2008 I heard a cricket when the thermometer temperature measured 46 degrees Fahrenheit (~8 degrees Celsius), but I didn’t count the chirps.

Figure 1. Using Crickets to estimate temperature. Notice the lack of data for temperature below 10 degrees Celsius. From cricket blog at http://www.globe.gov.

I knew about this temperature cut-off before observing crickets, from radar meteorologists. They see strong “clear-air” echoes when insects are flying. Figure 2 shows an example of insect echoes from a downward-looking radar used for research. The radar was mounted on a King-Air aircraft operated by the University of Wyoming. The data were collected while flying along a north-south track. So this is a north-south “picture” of insect plumes. It was 29 May 2002, and the air was quite warm — with temperatures well above 10 degrees Celsius.

Figure 2. Wyoming Cloud Radar image of “insect plumes” rising from the ground. 29 May 2002, on a north-south track over the Oklahoma panhandle (about 106 degrees West longitude). AGL means “above ground level.” Figure from Dr. Bart Geerts at the University of Wyoming.

Dr. Bart Geerts and his then graduate student Dr. Qun Miao found that the air was moving upward in the red and orange insect plumes, and that the air was moving down between them. They could see this because there were instruments on the King Air measuring the up-and-down air movement. I could feel the motion while I was on the plane: the airplane would get carried up when we crossed the “red” areas, and down in between. It was very “bumpy” where there were a lot of insect plumes.

You might think that the insects should be everywhere — after all, wouldn’t the insects be carried up by the upward-moving air and then back downward by the air between? Geerts and Miao found that the insects fly down in the updrafts, working hard to stay near the ground. This keeps the insects mainly in the rising air. Geerts and Miao even found that they could “measure” the updrafts and downdrafts by the radar alone by subtracting out the insect speed.

Here is another example of insect echoes, taken from weather radar in the southeast United States. The west-northwest to east-southeast-oriented light and darker blue patches are probably the “clear-air” (insect) echoes or small clouds; the yellows and reds are probably small rain showers.

Figure 3. Fair-weather echoes over southeast Georgia and Northern Florida in the SW United States.

Let’s summarize all these data in a table and a plot. First, the data. Plot this yourself, and see if you can think of any more “mileposts.” Or do some research to find some interesting temperatures, like the record high or record low temperature where you live. Or look at the FLEXE web site to see how hot it is near hydrothermal vents at the bottom of the ocean. You can use the graph to convert to the other units, or use the formula to convert back and forth (at the end of this blog).

Temperatures in Celsius and Fahrenheit

Figure 4. “Milestone” temperatures, in Fahrenheit and Celsius.

Methods of converting

You can use the table to make sure you are doing it right.

To convert Fahrenheit to Celsius:

Subtract 32 (notice you are subtracting Fahrenheit from Fahrenheit)
Then multiply by 5/9.

Or, if you prefer a formula, C = (F-32) x 5/9, where F is the Fahrenheit temperature and C is the Celsius temperature.

To convert Celsius to Fahrenheit:

Multiply by 1.8
Add 32
Or, in a formula: F = 1.8C + 32