physics

J. Stewart Marshall

J. Stewart Marshall is a physics topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand J. Stewart Marshall rather than just read about it. In short: John Stewart Marshall (18 July 1911 – 20 March 1992) was a Canadian physicist and meteorologist. Researcher for the Canadian government during the Second World war and then professor at McGill University from 1945 until his retirement in 1979, he was renowned for his research in cloud physics and precipitation, but especially for being a pioneer of weather radar.

Key takeaways

J. Stewart Marshall belongs to physics; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect J. Stewart Marshall to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of J. Stewart Marshall from memory before moving on to harder problems.

Reference excerpt

John Stewart Marshall (18 July 1911 – 20 March 1992) was a Canadian physicist and meteorologist. Researcher for the Canadian government during the Second World war and then professor at McGill University from 1945 until his retirement in 1979, he was renowned for his research in cloud physics and precipitation, but especially for being a pioneer of weather radar.

Biography

Early life Stewart Marshall was born on July 18, 1911, in Welland, Ontario, Canada. He attended Queen's University in Kingston where he earned his bachelor's degree in Physics and Mathematics in 1931, and then a master's degree in 1933 with a dissertation on scattering of electrons by metallic foils. After pausing to cure tuberculosis, he entered Cambridge University on a scholarship to study nuclear physics.

Second World War Marshall was recalled to Canada in 1939 to join the National Research Council of Canada in Ottawa and participate in the war effort. In Canada, he first worked on ballistics problems, then on experiments with a brand new invention, the radar. He was among the first to recognize that an artifact that sometimes obscured ships and planes on radar data was caused by rain and snow. In 1943, Marshall underwent thoracic surgery to fight a reappearance of tuberculosis and then took the lead of the "Stormy Weather" project by the Canadian Department of National Defense whose purpose was to find a use for these parasitic echoes. The analysis of precipitation backscatter properties made it obvious that the undesirable interference provided a new way to observe the atmosphere.

Career at McGill Just after the war, Marshall and R. H. Douglas formed the "Stormy Weather Group" at McGill University and continued their work. Different instruments were used by the group in research on the fundamental properties of precipitation. They were mounted at Dawson College, just south of the university's main campus. In the mid-1950s, the Stormy Weather Group's contribution included the study of cloud physics, radar precipitation echo properties, early radar application to storm surveys, and precipitation monitoring at wider scale. Some of the topics closely associated with Marshall are the raindrop size distribution, the study of the snow virga slope, radar signal fluctuation, coalescence and radar displays like CAPPI and HARPI. In 1968, the need for a more permanent radar led to the construction of the current observatory, which was named the J. S. Marshall Radar Observatory a little later in honor of the founder of the research group. At the same time Marshall was leading the research group, he was a professor of physics and meteorology at McGill University. The activities of the "Stormy Weather Group" attracted more and more graduates and, in large part, enabled the formation of the full-fledged meteorological department in 1959, the first in Canada. As director and founder, Stewart Marshall has profoundly influenced the teaching of meteorology, his department serving as a model for the creation of half a dozen programs across Canada.

Dissemination of knowledge Marshall and R. C. Langille, a colleague from Ottawa, were the only Canadians to attend the first radar meteorology conference at the Massachusetts Institute of Technology (MIT) in 1947. He organized the third conference at McGill in 1952 with two of his first PhD students: Walter Hitschfeld and Kenrick Gunn. Marshall also organized the 11th conference in Boulder in 1964, co-sponsored by the American Meteorological Society (AMS) and the International Union of Radio Science (IURS), and the 13th conference in 1968, again in Montreal.

Recognition Stewart Marshall and his doctoral student, Walter Palmer, became famous for their work on the distribution of mid-latitude raindrops that led to the relationship between radar return (Z for reflectivity) and precipitation rate (R): the ZR relation. Marshal has published many articles. He has served on numerous scientific and educational committees in Canada and the United States. He was a Fellow of the American Meteorological Society and served a term on the AMS Board from 1965 to 1967. He was elected a Fellow of the Royal Society of Canada in 1953. He has received several awards:

In 1961, the Patterson Medal of the Canadian Meteorological and Oceanographic Society In 1982, the Award for Outstanding Contribution to the Advance of Applied Meteorology by the AMS The Hugh Robert Mill Medal of the Royal Meteorological Society

References

David Atlas (1990). Radar in Meteorology: Battan Memorial and 40th Anniversary Radar Meteorology Conference. Boston: American Meteorological Society. p. 806. ISBN 0-933876-86-6. AMS Code RADMET

Also

Related articles J. S. Marshall Radar Observatory McGill Atmospheric and Oceanic Sciences

External links Works by or about J. Stewart Marshall at the Internet Archive "Papers of J. S. Marshall". American Meteorological Society.

Worked examples

Example 1 — a first encounter with J. Stewart Marshall

Start with the simplest possible case. Write down what J. Stewart Marshall claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In physics, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to J. Stewart Marshall before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about J. Stewart Marshall ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of J. Stewart Marshall

In research: J. Stewart Marshall appears in physics research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses J. Stewart Marshall in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: J. Stewart Marshall is common in secondary-school and first-year university syllabi. It links to neighbouring topics 1911 births, 1992 deaths, 20th-century Canadian physicists, so understanding it makes those chapters shorter.
In everyday life: Look for J. Stewart Marshall outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

Ask Teacher Smith questions about this articleOpens your AI tutor with a question about “J. Stewart Marshall” →

Affiliate

Preply — study more efficiently by working with a personal tutor. 50% off.

How to study J. Stewart Marshall in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what J. Stewart Marshall means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain J. Stewart Marshall out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is J. Stewart Marshall in simple terms?

Why does J. Stewart Marshall matter?

Because it connects several physics ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study J. Stewart Marshall?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on J. Stewart Marshall.