The Weather Myth: Lost Women of Science Podcast, Season 2, Bonus Episode

The Weather Myth: Lost Women of Science Podcast, Season 2, Bonus Episode thumbnail

We saw the story over-and-over: Klara Dan von Neumann, a computer programmer, was a pioneer of weather forecasting. Thomas Haigh, a historian who has studied the work of Dan von Neumann, said that he had not found any evidence to support this. How did this weather myth begin? That was the question we set out to answer. We set out to answer that question.

Note: We’d like to acknowledge the operators of the ENIAC who ran the 1950 weather simulation: Home McAllister and Clyde Hauff.

This podcast is distributed by PRX and published in partnership with Scientific American.




KATIE HAFNER: We have this database of about 200, 250 women who would be really good candidates for the podcast. Then we have these lively discussions where it is narrowed down and Klara comes up. You will spit when this happens. We thought she was very interesting because we heard she had done all the weather work. So, I was like, really? I didn’t know anything.

I Googled her and it said that you have this woman to be grateful for your weather app.

THOMAS HAIGH: You read it in the Smithsonian. It’s on Wikipedia. You assume there is some evidence.

KATIE HAFNER: If you look up Klara Dan von Neumann online, you’ll see variations on the weather app story again and again. And after five episodes focused entirely on Klara and the work she did, we haven’t mentioned one thing about weather. Did we miss something?

I’m Katie Hafner and this is Lost Women of Science ,, where we uncover the stories of scientists who haven’t received the recognition they deserve.

I hope my voice doesn’t sound too different, because I’m recording from my closet, on day 16 of COVID isolation.

This bonus episode is from our second season, “A Grasshopper in Very Tall Grass,” and was all about Klara Dan Von Neumann, Klari to her family and friends. She was among the first computer programmers.

This episode zeroes into the very first weather forecasts made on a computer. It’s also about the way someone’s legacy gets remembered–actually, misremembered–and how that gets etched into our collective historical memory.

JOHN KNOX: I’m John Knox. I am a professor of geography at the University of Georgia, Athens, Georgia. Klara von Neumann is my connection to her because I saw her name in one of the most renowned papers in my field’s acknowledgements section. I wanted to learn more about her.

KATIE HAFNER: When we first started looking into Klari’s story, we found article after article calling her the lost figure you should thank for modern-day weather forecasting, so that was intriguing. We reached out to John Knox, who was quoted in several articles. And, it turns out, John has known Klari’s name for a long time, ever since he first came across that famous paper on meteorology…

JOHN KNOX: When I was a graduate student, one of the first papers I think I ever read was called “Numerical Integration of the Barotropic Vorticity Equation.” And this was a landmark paper. It was the first paper to show that numbers could be used to forecast weather.

KATIE HAFNER: Attempts to predict the weather go back thousands of years. However, numerical forecasting is a relatively new …


JOHN KNOX: We didn’t have numerical weather forecasting for World War II, for example.

KATIE HAFNER: Numerical weather forecasting, the idea of using mathematical models to make weather predictions, had been theorized about at that point, but it didn’t really take off in a practical way until 1946.

That was when Klari’s husband John von Neumann and a group of scientists began to explore how electronic computers could be used to predict weather.

ARCHIVAL TAPE: This is weather. This is one of nature’s most mysterious mysteries. Recent experiments have shown that data from weather stations, radar observation stations, and guided weather rockets can all be fed into a computer in minutes.

KATIE HAFNER: In 1950, a team including Klari’s husband, Johnny, ran the first numerical weather prediction on the ENIAC, an early electronic computer. This was a huge achievement. It was huge because it took scientists six weeks to forecast the weather. You’d know what the weather was for May 15, but by the time you knew this, it was the end of July. Because they were faster than human calculations, computers like the ENIAC helped us get closer to weather forecasting in real-time.

In the historical paper explaining all this, at the bottom of the page, it states:

JOHN KNOX: “The writers wish to thank Mrs. K. von Neumann for instruction in the technique of coding for the ENIAC and for checking the final code.”

Klara von Neumann is, in my opinion, not only the help with the numerical forecast experiment but also a key participant. She should have been a coauthor on this important paper.

KATIE HAFNER: At Lost Women of Science, this kind of revelation is usually music to our ears. We are concerned about establishing the historical record and we are aware of many instances where scientists have not received their due. Women are especially often not credited, and acknowledged in acknowledgments or footnotes.

It’s not surprising that Klari did more than she was given credit for for these experiments. For starters, Klari was the expert in coding the ENIAC at this time. Her husband was also part of the team that did the weather work. It took place at Princeton’s Institute for Advanced Study, New Jersey, where Klari used to live and work.

We’ve seen her in that position before. You know–her right-place-right-time thing.

And, as always, when we had questions about Klari’s work we asked Thomas Haigh.

THOMAS HAIGH: All right, so yeah, the weather, the weather simulation.

KATIE HAFNER: Thomas Haigh is the co-author of ENIAC in Action. He is an expert on all things ENIAC. He’s also published more information on Klari’s programming than anyone else.

So when it came time to her weather work, we turned to that person…but we weren’t the first.

THOMAS HAIGH: So, uh when Ananyo was writing his book, he sent us the draft chapter on computing and we were able to, uh, I think help him steer it and make it even better.

KATIE HAFNER: Tom’s talking about Ananyo Bhattacharya, who wrote the new John von Neumann biography, The Man from the Future.

THOMAS HAIGH: And a little bit before the book was published, uh, we got a message from him saying like, did we miss something here? What’s this all about Klara von Neumann or the ENIAC weather simulations.

KATIE HAFNER: Ananyo had come across some references to Klari’s work on computerized weather forecasts. So, he also asked Tom about them.

THOMAS HAIGH: That was the first time I’d come across this article or the general idea that Klara von Neumann was the guiding force behind the numerical weather simulations.

KATIE HAFNER: As far as we could tell, this all started with a Forbes article from 2017. The headline read “How a woman you never heard of helped enable modern weather prediction” and was all about Klari. It was written by John Knox’s colleague at the University of Georgia.

JOHN KNOX: We just taught a class on hidden figures. It’s a question that I have as a professor: How do you encourage diversity? Our idea is to do this through curriculum.

KATIE HAFNER: John Knox told his colleague and his students about Klara von Neumann–how she was an overlooked programmer who, Knox believed, played a much bigger role in the computerized weather simulations than she had gotten credit for. So far so good.

John Knox is quoted in the article, saying that Klari trained the scientists on how to program and that she checked the final code–which is basically what the acknowledgement says in that 1950 paper.

About five months after the Forbes piece was published, the Smithsonian Magazine published another article about Klari’s weather work. John Knox is quoted again–he reiterates his belief that she should have been a co-author on the 1950 paper. Klari’s role in this article went far beyond advising scientists on their code.

Here is Tom Haigh reading the original text.

THOMAS HAIGH: Uh, so I’ll read that paragraph: “During these five weeks, Klara was a constant fixture. She was the one who approved the final code. She was involved in the ENIAC from its inception. According to journal entries by Charney, Platzman and other team members she played a significant leadership role in the meteorology program .”


KATIE HAFNER: Okay, this is how stuff gets lodged into the record. Klari was not only responsible for checking code and advising, but she was also the project’s helm. To be honest, I was skeptical when I first saw Klara von Neumann’s name. I thought this would be the story we’d tell. Our season would be about her leadership role in these numerical weather prediction predictions. She didn’t get the credit she deserved. We would go on about her weather modeling skills when people asked us who she was.

Then, we went to the Library of Congress and looked through the von Neumann papers …

KATIE HAFNER: So we’re sitting there, looking through this stuff and I see these folders that are just meteorology meteorology, and I think great, here it is. This will explain everything. Klari is a completely different story.

KATIE HAFNER: That’s me. I’m reminiscing on our time at Library of Congress with Sophie McNulty (one of our producers).

SOPHIE MCNULTY: And during lunch, we were waiting in line to get our food. Katie, I remember your face. You were like, guys. I don’t know if there is a season.

KATIE HAFNER: I’m like, oh my gosh. We’ve made it this far. We had been on a long road with Klari and now we have found nothing.

SOPHIE MCNULTY: And immediately, you know, my heart’s racing and in my head I have all these doubts, but I’m, I’m trying to calm Katie down and I’m like, there’s definitely stuff. So I was on my phone, frantically pulling up quotes, and being like, “Look, here’s proof that she did it.”

KATIE HAFNER: Sophie remembered reading passages about Klari’s coding work in George Dyson’s book, Turing’s Cathedral.

SOPHIE MCNULTY: And Katie knew George Dyson and immediately emailed him and–

KATIE HAFNER: And that was that.

KATIE HAFNER: Once we spoke with George, all the pieces started falling into place. Klari’s work in the Monte Carlo Method, as well as with nuclear weapons, was revealed to us. We had our season.

But the question of Klari’s role in weather simulations kept bugging me and Tom Haigh. He had taken a microscope to examine all the material.

THOMAS HAIGH: I didn’t come across correspondence from her related to this, but we do have the correspondence that’s going backwards and forwards between the people, uh, in the ENIAC group and the people in the numerical meteorology group at the Institute for Advanced Studies. The footnote is the only way we know she did anything.

KATIE HAFNER: This idea, that Klari was the computer scientist to thank for your smartphone’s weather app–it was spreading. It was then published in Forbes and Smithsonian magazines, and finally reached Guardian UK. Tom was certain it was wrong.

THOMAS HAIGH: So it’s saying that she was doing the same job for the meteorology project–being hands on, writing the code, working with the punch cards, setting the thing up–that she did with the Monte Carlo simulations.

The problem is that I haven’t seen any evidence in the archival evidence, or in the work of others that supports this idea.

There is no evidence that she was part the group that ran the calculations. She clearly wasn’t the one who was doing the punch cards.

KATIE HAFNER: So while Klari may have advised the team or reviewed the code the team wrote, it seems unlikely that she was one of the main programmers, and there’s little evidence indicating that she was actually on location with the ENIAC to run the weather simulations.

Tom points to the fact that there isn’t always a paper trace. It is possible that Klari was speaking face-to-face with Princeton residents, but we don’t know how to find out. If you have heard anything about Tom, you will know that he is anything but careless. He takes the time to do it right and cares about the success of others, especially when they are the ones who have to tell the rest of the globe.

So Tom sent a long email to the Smithsonian explaining each error he found in the article.

THOMAS HAIGH: The response I got was, “Dear Mr. Haigh, Thank you for your email to the Smithsonian magazine regarding the article, ‘Meet the Computer Scientist you Should Thank for Your Smartphone’s Weather App.’ Your response is being shared with the digital editorial director.” And that was it.

KATIE HAFNER: So we wrote to Smithsonian magazine and the editor we heard back from said they did get Tom’s letter, but didn’t follow up at the time. I explained that there were significant problems with the story. They made significant changes. That is a win for us.

In the meantime, John Knox and I discussed Tom’s findings with him: Klari was the expert in coding for ENIAC, but there was no evidence that she coded or ran the program to simulate the weather. Maybe that acknowledgment in the 1950 paper was entirely appropriate for what she had done. Perhaps she had been an advisor, and not more.

JOHN KNOX: So it may be that she was not intimately involved with the production of the weather forecast code, but that she set up everything for that. I’m not 100% certain about that.

KATIE HAFNER: Together, we decided to take a look at the 1950 paper where it all began. We noticed that Klari is not the only one who thanked at the end …

JOHN KNOX: So there are a couple of people named that may have actually been doing the computations.

KATIE HAFNER: The last line of the acknowledgments reads…

THOMAS HAIGH: “We’re also greatly obliged to the staff of the Computing Laboratory of the Ballistics Research Laboratory for help in coding the problem for ENIAC and for running the computations.”

KATIE HAFNER: So maybe Klari didn’t actually do much on the computer itself for this project. Those operators probably deserve the credit. Klari gets a lot of attention.

KATIE HAFNER: It’s more than a footnote. It’s an-she in the acknowledgements.


KATIE HAFNER: And she’s the very first.

JOHN KNOX: She is the first. You’re making me reconsider my opinion based on the details of her contribution. It would have been generous of her to give me a co-authorship. Um, I would have done it.

KATIE HAFNER: Coming up, we look at the danger of “the great woman theory of history.” I’m Katie Hafner and this is Lost Women of Science.


THOMAS HAIGH: “Unlike computing itself, the history of computing has no automatic error checking and correcting devices.”

KATIE HAFNER: Tom Haigh’s reading a quote from physicist Nick Metropolis. It’s true that computers can sometimes stop running if there is a problem with the code or if something is missing.

But history can make it spiral if one event is misremembered. It is recorded in the record, from a lecture in a classroom to an article online to Klara von Neumann’s Wikipedia entry. And I get it. It’s a great story about the woman who invented modern weather forecasting. It’s not the right story.

This bonus episode is our attempt at getting it right. We have to ask: If Klari is getting the credit…who else is? We are missing something?

CAITLIN RIZZO: This is one of 10 of the notebooks just for meteorology. There are many other notebooks.

KATIE HAFNER: Caitlin Rizzo is the archivist at the Institute for Advanced Study, that haven for super geniuses.

CAITLIN RIZZO: You know, it’s many, many days, like each notebook, roughly maps onto a month of labor of someone sitting at this computer and just writing down, this is what calculation was off.

KATIE HAFNER: After the 1950 paper came out, a team at the Institute for Advanced Study continued to work on numerical weather forecasting. Caitlin is currently researching their efforts. Caitlin is an archivist and spends a lot time thinking about how someone’s ideas, legacy, and experiences are documented and preserved.

CAITLIN RIZZO: I do have a photo of some of the women workers on the project on the table as well and a lot of them remain, um, unidentified. We’ve tried to identify some of these women by asking people who were involved in the project. Because this was a lot of computing work for women.

KATIE HAFNER: And while this is an ongoing project, there are some names that Caitlin is sure of.

CAITLIN RIZZO: So this is Hedi Selberg’s work.

KATIE HAFNER: Caitlin points to a typewritten report with the title “Explanation to the Code for the Astrophysical Problem”. We know Hedi’s identity partly because she is credited on the document and also because she was married with someone on the faculty of the Institute for Advanced Study. Klari was also known as Hedi, an “institute spouse “.

CAITLIN RIZZO: They are these amazingly brilliant women who maybe were not as credited in academia, right? They were there and did amazing work.

KATIE HAFNER: And Hedi Selberg wasn’t the only one.

CAITLIN RIZZO: Um, so I mentioned the Smagorinskys. That’s, that’s one.

KATIE HAFNER: Joseph Smagorinsky is a big name in meteorology–he worked on the 1950 simulation, and he went on to expand the possibilities for weather modeling with computers.

Who were the programmers and who did the calculations? Margaret Smagorinsky, Joseph’s wife, was at least one of them. She was a statistician for U.S. Weather Bureau.

CAITLIN RIZZO: And, um, her husband is incredibly noted, but she didn’t have a Wikipedia page when we first contacted the family. We are working on that now.

KATIE HAFNER: Caitlin has a word for the kind of work that often goes missing from the historical record…

CAITLIN RIZZO: Maintenance. It is difficult to capture the work of maintenance, of caring about every day in and outside, in the archives. The archives are looking for what is distinctive and memorable.

KATIE HAFNER: For Caitlin, and for us, making sure that people are acknowledged is really important.

CAITLIN RIZZO: We’re trying to find them again and to do the same kind of reparative work that you’re doing to, to highlight that maybe they weren’t in the official ledger, but they are part of the story.

KATIE HAFNER: At Lost Women of Science, we try to find the work that didn’t always get top billing. We might be tempted, therefore, to read between the lines. John Knox was a good listener and I realized that his well-intentioned efforts to highlight Klari’s contributions were misdirected. He ignored that footnote and went with it. While there are people you can thank for your smartphone’s forecast app, Klara von Neumann was not one of them. In fact, she may not have played as important a role.

Giving Klari credit is unfair to Klari and to programmers and operators whose names may not be known.

John Knox was changing his mind by the end of our conversation.

JOHN KNOX: So I guess I would go back now and maybe modify my comments. Based on what I have seen up to now, I don’t think she should have been a author, but it wouldn’t have happened without her. It’s, it’s in one those gray areas. I tend to be a bit liberal with co-authorship, because I believe it’s important um recognize the people without whom this thing could not have been accomplished.

KATIE HAFNER: We think that’s important, too. In fact, that’s part of what bothered me so much about this idea that Klari was the woman behind modern weather forecasting, as if all it took was one woman. Here’s Tom Haigh again.

THOMAS HAIGH: We tend to think of history as something that is about great geniuses, having ideas that are decades ahead of their time and changing the world through their brilliance. In many ways, this is the only story that popular movies and books want to tell about science or technology.

KATIE HAFNER: And that’s a problem because…

THOMAS HAIGH: You get to be a lone genius by, you know, having a whole support infrastructure around you, of people who are lab technicians or secretaries, or performing other kinds of support roles. These are the people who are not remembered by history, because all the credit goes the lone genius. And that’s why I don’t believe the solution is to find female geniuses to celebrate the men the same way.

KATIE HAFNER: When Tom and his co-author Mark Priestley were working on ENIAC in Action, they made a point of tracking down as many names as they could.

THOMAS HAIGH: We tried to talk about the women who actually, you know, built the machine hands-on. We paid tribute to the work of the project secretary who was one of only a few people who worked full-time on ENIAC and stayed with the machine throughout its construction.

I think that if we can think about more types of contributions to being meaningful, then we can recognize the contributions that women made to science.

KATIE HAFNER: And that’s the power of revisiting the historical record. We must fundamentally alter our perceptions of progress and contributions if we are to challenge patriarchy. It’s not about rescuing a single woman who was overlooked or slighted. We are not trying to replace the singular male genius with female versions. It’s not Lost Women of Science or what we do here.

We must acknowledge the many people who are not recognized for their contributions to innovation. These include the lab techs, administrators, janitors and childcare workers. We must stop thinking of disruptors and instead focus on the many contributors.

This is why our credits are so long.


This was Lost Women of Science . This initiative was made possible by my co-executive producers Amy Scharf, Sophie McNulty and Sinduja Srinivasan. Senior editor Nora Mathison, Elizabeth Younan, and our engineers at Studio D Podcast production: Simeon Church, and Dylan Garven.

Thanks to Sarah Witman and Brian Wolly from Smithsonian Magazine, who know I was there.

We are grateful to Mike Fung and Cathie Bennett Warner, Jeff DelViscio and Meredith White, Jeff DelViscio and Meredith White.

Thanks to the Computer History Museum, Paula Goodwin, Nicole Searing, and the rest of Perkins Coie’s legal team, as well as to the Institute for Advanced Study and the Library of Congress Special Collections for their assistance with our search.

Many thanks to Barnard College for their support during the Barnard Year of Science. They are a leader in encouraging young women to pursue STEM careers.

Lost Women of Science is funded in part by the Gordon and Betty Moore Foundation, Schmidt Futures and the John Templeton Foundation, which catalyzes conversations about living purposeful and meaningful lives.

This podcast is distributed and published by PRX in partnership with Scientific American.

You can learn more about our initiative at, or follow us on Twitter and Instagram. Find us @lostwomenofsci. That’s @ lost Women of S-C.I.


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