Thursday, 23 May, 2013

Synopsis: Hurricanes, the most powerful and dangerous storms of all, get their energy from the difference in temperature between a warm ocean and a cooler atmosphere. A century ago, hurricanes blew in with almost no warning; now they are tracked from the sky and space, and every year, warnings get a bit more useful. How [...]

How do hurricanes form? How do we predict their paths? How can we improve predictions?

We love accurate weather forecasts, but the weather satellites they rely on are nearing the boneyard. Some replacements have crashed into the ocean, others are in financial limbo. Be very worried about our fragile planet: these satellites also track climate, ice, fire, and the health of forests and ocean!

Classroom Activity Page: The poles are fascinating, partly because they are such difficult places to visit, work and live. They still guard many mysteries that we’d like to unravel, including the survival of polar animals, the history of ancient peoples, and the understanding of Earth’s climate.

If you saw something like this falling from the sky, you might think that the weather outside was indeed frightful. But this dumbbell shaped object is, in fact, a super-magnified snowflake — yes, a snowflake. Not so frightful after all. This particular snowflake is a capped column, one of many types of snowflakes. The fuzzy [...]

Tornadoes need wet air, dry air, and wind shear. What explains the big improvement in tornado prediction? Is climate change boosting these storms?

Is Madison, Wisconsin in a snow belt? What is the origin of the term? While the lakes around Madison provide many winter recreation activities, the local lakes do not yield a snow belt. Map by Pierre cb We refer to agricultural regions in the United States as ‘belts’, such as the cotton belt and wheat [...]

Watch for steam devils in late November/early December Steam Devils in Wisconsin One of the many advantages of living near large lakes in temperate climates is the steam fog that shrouds them in fall and early winter. Fog is essentially a ground-hugging cloud, composed of tiny liquid water droplets. Steam fog will develop at this [...]

When does winter really start in Wisconsin? Photo: MODIS Image Gallery by Liam Gumley, SSEC (Space Science and Engineering Center, UW, Madison). State outline barely visible under snowcover (click image to enlarge), this is Winter in Wisconsin. The beginning of astronomical winter doesn’t occur until the Winter Solstice, which is usually between December 20-22. On [...]

What is the difference between a ‘warning’ and a ‘watch’? A weather watch indicates the possibility of hazardous weather, while a warning means that hazardous weather is occurring, is about to occur or is very likely to occur. A watch is intended to provide people with enough time to set safety plans in motion for [...]

Why are clouds white? Photograph of Cumulus clouds in fair weather taken by Michael Jastremsk Clouds are made of water and clean water is clear. So why are clouds white? Because clouds are made of billions of small water droplets and ice crystals. When light beams interact with particles suspended in air, some of the [...]

What does a 60 percent chance of precipitation mean? The probability of precipitation (fondly known as PoP) has been part of weather forecasts since the late 1960s, and is the only forecast element that includes a probability. Unfortunately, there is confusion about the exact meaning of a “60 percent chance of precipitation.” Part of that [...]

Rainbows are one of the wonders of the natural world: But why do you sometimes see one rainbow, and other times a double? Why do you always see rainbows with your back to the sun? How do they really work? Operate your own rainbow, then find out! OPERATING INSTRUCTIONS: CHOOSE YOUR ‘BOW: • Primary shows [...]

Tornadoes can happen whenever atmospheric conditions are suitable, says Steve Ackerman, professor of atmospheric science at UW-Madison. Over the years, Wisconsin has had at least one tornado in every month except February. “To get any severe weather, we need really warm, moist air near the ground, and cool air aloft, which is typical of the [...]

Scott Bachmeier, a research meteorologist at the Cooperative Institute for Meteorological Satellite Studies at UW-Madison, says that particles in the air scatter light. In the day, the particles scatter more violet and blue light, but our eyes are more sensitive to blue light — that’s why the sky appears blue. Thunderstorms, which can be the [...]