Meteorology (WEATHER & CLIMATE) Encore with Marshall Shepherd

Dr. Marshall Shepherd, a research meteorologist and former NASA scientist, has spent his career studying the hows and whys of weather, not just forecasting it. In this conversation, he clears up the difference between weather and climate, explains what forecast probabilities actually mean, and walks through the physics behind storms, snow, heat, and humidity. He also addresses common misconceptions, the limits of prediction, and why a warmer atmosphere can make snowstorms worse.

Weather vs. climate, and why snow doesn’t disprove warming

Shepherd uses a simple analogy: “Weather is your mood and climate is your personality.” A single cold day or snowstorm tells you nothing about long-term climate trends, just as a bad mood doesn’t define a person’s character. He fields this confusion regularly—someone will tweet him about shoveling snow and ask what happened to global warming. His response is that it’s winter in Boston; snow is expected. The real issue is that a warmer atmosphere holds more water vapor, about 4% more per degree Fahrenheit, thanks to a principle called the Clausius-Clapeyron relation. That extra moisture feeds all kinds of storms, including snowstorms. So a warming climate can actually produce heavier snowfalls, not fewer.

How forecasts work, and what 30% chance of rain really means