Dan’s Wild Wild Science Journal

Inside view of a globular cluster from The Harvard-Smithsonian Center for Astrophysics.

I love Astronomy, and many times I write something about it here to teach MYSELF something. Atmospheric Science is my field, but I thoroughly enjoyed the two undergrad astronomy courses, and the graduate course I took. This means I know just enough about Astronomy to be dangerous! Pilots are taught just enough Meteorology to be dangerous!

A "globular cluster" of stars. This one was first discovered by Edmund Halley who later got into comet predictions. (Astronomers aren't any better than Meteorologists in thinking up names for things!)

Frequently, I hear someone say something along the lines of “how do we possibly know what the temperature was like 10,000 years ago? There were no thermometers around!”

A similar refrain is often made with regard to the age of the Universe. I’m sure you have thought of other examples. I know I have. How do we know what dinosaurs ate for instance? No, we have not found any ancient menus from the town of Bedrock!

You put enough pieces together though, and you can have a real Yabba Dabba Doo moment!

In Science, one piece of information can be very valuable, but no one would state something like the examples above based on just one piece of the puzzle. What Dinosaurs ate is based on hundreds if not thousands of independent pieces of evidence. Same for the temperature 10,000 years ago. Fossil trees, ice cores, seabed cores, etc.

That’s how we know.

These are the fascinating things about science. What we know can be fabulous, but learning HOW we know, now that is the fun stuff!

Andromeda Galaxy from Hubble Space Telescope. It has globular clusters orbiting it. At least 500 of them!) Our own Milky Way galaxy has a bunch as well. M31 G1 is a globular cluster. M31 is Andromeda. Picture courtesy NASA McDonald Obervatory/Stardate.com

Take globular clusters. I want to use it as an example of how we can get a glimpse of how old the Universe must be. Many times in Science, you cannot get an exact answer, but you can constrain the number you are looking for. Globular clusters for instance tell us the Universe is “at least x billion years old”.

Read on- it’s a neat piece of deduction!

First, you ask, WHAT’S A GLOBULAR CLUSTER???

Nothing more than a cluster of stars. A mini galaxy in the shape of a ball. Thousands and more likely millions of suns. Some like our own, and others much larger and smaller than ours. Over 150 globular clusters are known to orbit our own Milky Way Galaxy.

Globular clusters formed out of Hydrogen and Helium like all the galaxies. In the very early Universe, that is all there was. Look around you. EVERYTHING you see that is not Hydrogen or Helium, was made in a star. Do you have a gold ring on? If so, it was made in a supernova. Look at yourself in the mirror. Yup, you too are made of star dust.

So is the computer I am typing on, but the good folks at Apple in California have done a lot with the raw elements the stars made!

Now, imagine a huge vast cloud of Hydrogen and Helium that slowly starts clumping together due to gravity. As it compresses it heats up. Knots of gas form. Some big knots and some small ones. Eventually the pressure is so great that nuclear fusion begins and stars form.

Some giant, hot blue stars and some like our own sun. Many more smaller “red dwarf” stars.

The Hertzsprung-Russell Diagram. Big stars burn bright, but live short lives. (From: http://cse.ssl.berkeley.edu/bmendez/ay10/2002/notes/pics/bt2lf1509_a.jpg)

Here is the neat part. All stars are not created equal. You might think it would be great to be a giant blue star visible for a billion light years in all directions. Not so! Big stars use up their fuel very rapidly. They may burn for only a few million years. Smaller stars like our sun, can burn for 10 Billion years. Smaller stars still can burn even longer.

Now imagine that we use one of the giant telescopes to look at a bunch of globular clusters. We can look at them in visible light and infrared and even in x-ray light using the Chandra X-Ray telescope.

It turns out that most of the globular clusters around our own Milky Way Galaxy and indeed many of the ones we see elsewhere, are all missing something. They are missing the giant stars.

Where did they go? Did the globular cluster just not form any when it formed from the giant cloud of Hydrogen and Helium and dust?

Not likely.

They were there. They lived out their lives, and either exploded as some big stars do or turned into white dwarfs, a fraction of their old size with such low luminosity, that we cannot see them anymore. (The deaths of stars is one of the most fascinating parts of astronomy)

If we know how long stars of a certain size live, (and we think we do!) then we can look at a globular cluster, and by seeing what stars are missing, we can estimate it’s age! Astronomer Alex Filippenko says its like walking into a room with a burning candle. If you know how fast it burns, and how tall it was originally. It’s easy to figure out, how long ago it was lit!

Now if that doesn’t make you go Gee Golly, then you have no imagination what so ever!

Many globular clusters are measured to be over 12 billion years old! Since the Universe they are in has to be at least that old itself, we can now say the Universe is at least 12 Billion years old!

Techniques like this (and many others using different astronomical objects) have allowed Astronomers to say with growing confidence that they have constrained the age of the Universe to 13.7 Billion years old. Plus or minus 120 million years.

I just ordered my first pair of astronomical binoculars and am told you can see globular clusters with them. Look for a guest post soon on how to buy your first telescope.

Later,
Dan

Note: If any experts in Astronomy read this, and find that I have gotten something wrong, PLEASE email me. I will post it, and correct the error, and we can all learn more about the stars. Keep in mind that I write this for a general audience, so let’s not get into deriving the Hubble Constant- but I am anxious to know more. I would be honored to have your thoughts and to share your knowledge.

Sources: Astronomy 10- Alex Filippenko UC Berkely
NASA/Wikipedia
The COSMOS- Astronomy in the New Millenium A. Filippenko Jay Pasachoff
McDonald Observatory/Stardate

Seattle- Dan's pic

Back in the 1970’s there was a popular TV show called “Here Come the Brides”. I never watched it much, but I loved the theme song “Seattle” by Bobby Sherman. seattleclip

Seattle is one of my favourite places. I even went there on my honeymoon! (Yeah, I know, only a weather geek would go to a city renowned for rain and drizzle, on their honeymoon.  It’s a weather thing.)

Me and Marian in Seattle Oct. 1983

Today was anything but typical for Seattle. It was brutally hot. Now, everyone thinks that Seattle is a rainy place. They do have a lot of cloud and frequent drizzle, but there are plenty of places that get more rainfall each year. Like my house here in Huntsville Al. Yes, it’s cloudy a lot, but a clear summer day can really bring the bluest skies you’ve ever seen.

Today, however, it was different. Record highs anywhere are infrequent, but a record ALL TIME HIGH is very rare. Seattle hit 39.5C Smashing there old all time high by 1.5C. (39.5C is 103F on the old Fahrenheit scale, used only in the USA now)

Newscasts in Seattle showed people standing in long lines to buy air conditioners in the intense heat. Most people living around Puget Sound do not have them. It rarely gets above 30C in Seattle..much less 40C!

Mount Rainier August 2006 Dan's pic

So, while Chicago has it’s coolest July in decades, the folks in the Pacific NW continue to bake. Mother nature tends to balance out the planet. When one part of the world is unusually hot, you can usually find somewhere else where it is unusually cold. When we get cool snaps, I will often get emails from people asking what happened to “Global Warming”??

The June temps. globally actually put this in perspective.

June 2009 was the 2nd warmest on record worldwide. From NOAA/NCDC

If you lived in Denver in June, you might think summer had disappeared. It was much different for almost all of the rest of the planet, with unusually warm conditions. Notice the warmth in the far north. This has been predicted to be a result of increasing greenhouse gases, for over two decades. It seems to be showing up very frequently these days.

Important to note here, that it’s very bad science to blame an unusually hot, or cold day on climate change. All you can say is, that if the high temp. is like a roll of the dice, the high numbers will keep coming up more often, in more places, than the cold ones.

The language of science is not proof. It’s probability!

Taichiro has put together a series of videos on El Nino that are superb! I learned some new things and I suspect most Meteorologists who are not active in researching ENSO science will too.

You can see them by clicking on the image below! Taichiro is working on his Phd. at Duke.

This last week brought an update on the Arctic sea ice from the NSIDC folks. It also saw the publication of a paper in SCIENCE that made almost all of us who follow climate science, sit up and notice. Neither is particularly good news, and that may be an understatement.

Courtesy National Snow Ice Data Center (NSIDC-NOAA)

First the ice- or lack of same.

2007 saw the lowest amount of Arctic Ocean ice on record. I happened to be in the High Arctic in August (The record low was reached the following month). We traveled down a hundred plus miles of the fabled NW Passage and saw very little ice at all. The sudden drop in 2007 stunned the science world. The best guess of the IPCC were that the Arctic ocean would not be substantially ice free in Summer until around 2090. Those days are gone.

At the current rate of melt, the ice may be mostly gone by 2050 and some scientists are betting 2040.

It’s not just the coverage of ice that is changing. Far more dramatic in my opinion is the changes in thickness. The thicker ice that survives for multiple summers is disappearing. This is a strong indication that the summer melt will accelerate quickly.

Ice thickness changes from NASA/NOAA ICESAT (Click to enlarge)

What will the September bring? It’s looking more and more as if we may approach the 2007 melt. We are already running ahead of last years near record.

It is important to understand that the ice will not just drop a little more each year. There are many factors that govern how much ice melts each year. Ocean currents, and prevailing winds are two of the most important. The year to year fluctuations are caused by weather. The long term decline is caused by Climate.

Now onto clouds..

The affects that clouds have on our climate is one of the least understood aspects of climate. While you may think that clouds act to reflect the suns energy and act to cool the planet, this is not always the case. Clouds at night, trap heat in. Thin cirrus clouds actually cause warming and a deck of low clouds in daytime does act to cool the planet.

Someone told me awhile back, that we did not need to worry about climate change because as the earth got warmer, the oceans would evaporate more and the extra clouds would cool us right down. (and we did all that radiation Physics for nothing!)

Most climate models have assumed that clouds will increase a bit and act to cool as we warm up. This is a negative feedback. If the paper published in Science this week is right, the truth is just the opposite!

Amy Clement from the Univ. of Miami and others have published the results of a detailed study of clouds over the Pacific. Using surface and satellite records, they found that as the ocean warmed, the clouds DECREASED! This is a positive feedback. Fewer clouds will allow more sun in, causing more warming and even fewer clouds.

From Clement et al.,Science; July24,2009

They found that the one climate model that seems to show this best is the Hadley Center model in the UK. It’s one of the main models and is known for having a higher sensitivity.

The Climate sensitivity is defined as the warming we would expect for a doubling of the CO2 levels. The IPCC has given a range of 2.5C to 4.0 C for this and you will often see the mid range of 3C quoted in mass media. We will likely reach this doubling in 40-60 years. If Clement and her fellow authors are right, the climate sensitivity might be closer to the Hadley model at 4C.

This would mean that we have less time to reduce our emissions, and the goal of holding the warming to 2C, will be very difficult to reach. Even with more massive cuts in emissions than we thought. Note the IPCC will still be correct (albeit at the upper range) in their forecasted climate sensitivity!

Science does not deal in certainties, the language of science is probability. Even if we were to reach the emissions goals set out by politicians at the G8 awhile back, we would still have a 50% chance of exceeding 2C. And, that is if Clement et al. are wrong!

I told you the news wasn’t good.

There was an intriguing paper in Science this month about tropical cyclone predictions.

Every spring, there is considerable media attention to the forecasts from Colorado State and NOAA, on how many hurricanes we can expect.  Every  spring, I remind my viewers that these forecasts have little skill. Nonetheless, you cannot learn to forecast something unless you try and trying brings new knowledge and insight. So have at it, but tell the public that there is low confidence in the forecast.

The connection between El Nino, and La Nina, and Atlantic hurricanes has long been known, and the current ENSO phase is an important ingredient in these seasonal forecasts of tropical cyclone activity. Specifically, an El Nino tends to increase wind shear over the Atlantic and reduce the number of hurricanes, while La Nina does pretty much the opposite. An El Nino seems to be brewing right now and may hold down the number of storms this year.

El Nino, La Nina and Cen. Pac. Warming- image From Kim et al. in Science 3 July 2009- complete cite in text.

Some El Nino years have turned out to rather active though, and three scientists at Georgia Tech. (H.-M. Kim, P. J. Webster, J. A. Curry, Science 325, 77 (2009) may have discovered one reason!

The answer?

CENTRAL PACIFIC WARMING (CPW)

El Nino is a warming of waters in the Eastern Pacific. Eastern Pacific Warming (EPW).   La Nina is a cooling of waters in the Eastern Pacific (EPC). There also seems to be a cycle of warming in the sea surface temps. of water in the Central Pacific. This (CPW) warming has a strong connection to hurricanes too. Not only that, but it has a strong connection to storms that affect the Gulf and East coast of the U.S, Mexico and Canada! Apparently even stronger a connection than El Nino.

Greg Holland from NCAR wrote a perspectives piece on the paper by Webster-Kim and Curry and speculates that perhaps some El Nino events in the past have been misidentified even.

From Hye Mi Kim and colleagues. Red is >normal T. Cyc. activity. Blue is below normal.

Wait, there’s more!

Forecasting the development of an El Nino, or La Nina ahead of time is very difficult. Especially if we are between cycles. There is a forecast wall, in the early spring, that makes it nearly impossible. So, insurance companies and residents cannot know whether an El Nino or La Nina is coming for hurricane season. These CPW events are, according to Kim et.al. MUCH more forecastable!

So they may have found a new method of forecasting tropical cyclone numbers, that is more accurate, and easier to forecast than in the past!

You do that, and you get published in what is perhaps the most distinguished peer reviewed journal, of them all!

SCIENCE.

Later,
Dan

ps: If you want to really understand how El Nino’s begin and end, then Taichiro Sakagami has made it easy. His videos are highly recommended.