astronomy

John Christy

John Christy is a astronomy 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 John Christy rather than just read about it. In short: John Raymond Christy is a climate scientist at the University of Alabama in Huntsville (UAH) whose chief interests are satellite remote sensing of global climate and global climate change. He is best known, jointly with Roy Spencer, for the first successful development of a satellite temperature record, and for his rejection of the scientific consensus on climate change.

Key takeaways

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

Reference excerpt

John Raymond Christy is a climate scientist at the University of Alabama in Huntsville (UAH) whose chief interests are satellite remote sensing of global climate and global climate change. He is best known, jointly with Roy Spencer, for the first successful development of a satellite temperature record, and for his rejection of the scientific consensus on climate change.

Early life and education A native of Fresno, California, Christy became interested in the weather when he was a child. He became curious why the weather in the San Joaquin Valley was so different from that of the Sierra Mountains. He has recalled that "I built my first climate datasets when I was 12, using a mechanical pencil, graph paper, and long-division (no calculators back then.) I've been a climate nerd ever since." He received a BA in mathematics from California State University, Fresno in 1973, and an MS and PhD in atmospheric sciences from the University of Illinois at Urbana–Champaign in 1984 and 1987. His doctoral thesis was titled, An investigation of the general circulation associated with extreme anomalies in hemispheric mean atmospheric mass. Prior to his scientific career, Christy taught physics and chemistry as a missionary teacher in Nyeri, Kenya from 1973 to 1975. After earning a Master of Divinity degree from Golden Gate Baptist Seminary in 1978 he served four years as a bivocational mission-pastor in Vermillion, South Dakota, where he also taught college math.

Career He is the distinguished professor of atmospheric science and director of the Earth System Science Center at the University of Alabama in Huntsville (UAH). He was appointed Alabama's state climatologist in 2000. For his development of a global temperature data set from satellites, he was awarded NASA's Medal for Exceptional Scientific Achievement and the American Meteorological Society's "Special Award." In 2002, Christy was elected Fellow of the American Meteorological Society.

Satellite temperature record

Since 1989 Christy, along with Roy Spencer, has maintained an atmospheric temperature record derived from satellite microwave sounding unit measurements (see: satellite temperature record). This was once quite controversial: From the beginning of the satellite record in late 1978 into 1998 it showed a net global cooling trend, although ground measurements and instruments carried aloft by balloons showed warming in many areas. Part of the cooling trend seen by the satellites can be attributed to several years of cooler than normal temperatures and cooling caused by the eruption of the Mount Pinatubo volcano. Part of the discrepancy between the surface and atmospheric trends was resolved over a period of several years as Christy, Spencer and others identified several factors, including orbital drift and decay, that caused a net cooling bias in the data collected by the satellite instruments. Since the data correction of August 1998 (and the major La Niña Pacific Ocean warming event of the same year), data collected by satellite instruments have shown an average global warming trend in the atmosphere. From November 1978 through March 2011, Earth's atmosphere has warmed at an average rate of about 0.14 C per decade, according to the UAH satellite record. Christy was a lead author of a section of the 2001 report by the IPCC and the U.S. CCSP report Temperature Trends in the Lower Atmosphere – Understanding and Reconciling Differences. Christy also signed the 2003 American Geophysical Union statement on climate change. Christy has also performed detailed reconstruction of surface temperature for Central California. He found that recorded temperature changes there were consistent with an altered surface environment caused by increased irrigation for agriculture, which changed "a high-albedo desert into a darker, moister, vegetated plain."

… excerpt ends here. Continue reading the full article.

Worked examples

Example 1 — a first encounter with John Christy

Start with the simplest possible case. Write down what John Christy claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In astronomy, 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 John Christy 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 John Christy 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 John Christy

In research: John Christy appears in astronomy 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 John Christy 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: John Christy is common in secondary-school and first-year university syllabi. It links to neighbouring topics American climatologists, California State University, Fresno, alumni, Fellows of the American Meteorological Society, so understanding it makes those chapters shorter.
In everyday life: Look for John Christy 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.

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How to study John Christy in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what John Christy 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 John Christy out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is John Christy in simple terms?

Why does John Christy matter?

Because it connects several astronomy 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 John Christy?

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 John Christy.