Tag Archive

Answers: heating, cooling degree days

By Jack Williams ©2015

Q: Several years ago, you wrote a short article for USA TODAY about heating degree days. I have depended on that article, and its links, to monitor the heating and cooling degree days in my area.  Now, I cannot access this article any longer through a USA TODAY search and I'd really like to have access to it.  I would... »

Answers: Finding wind data

By Jack Williams ©2015

Q: What is your favorite source for near real time surface wind visualizations in the mid Atlantic region. I need the information for balloon flight planning in the field. Curt, Falls Church, Va. A:  I’ve yet to find any really good visualizations for surface winds because none show the winds in any real detail. That said,  best that I've found are NWS... »

Answers: Supercooled water

By Jack Williams ©2015

Q: How can water that is below 32 degrees F (zero degrees C) remain in liquid form and not freeze? That is, become "supercooled"? Matt, LaGrange, Ga. A: The best way to begin understanding how supercooled liquid water forms is to forgot what you've been told about water "freezing at 32 degrees F." This is really the temperature at which ice... »

Answers: Aircraft altimeter errors

By Jack Williams ©2015

Q: Can you help me understand in very simple terms altimeter error when flying from high to low pressure areas and from low to high areas?  I am studying it but its just not clicking.—Mark, Noblesville, Ind. A: To answer  your question I'll begin with some basic information about aircraft altimeters and then use the diagram below to help you see... »

Suggestions for hurricane-oil spill coverage

By Jack Williams ©2015

With Hurricane Alex no longer a threat to the people and vessels working to stop and clean up the Gulf of Mexico oil spill, reporters, newscasters, editors, and other news people can take a breather and think about ways to improve coverage when the next hurricane moves into  the Gulf of Mexico. One of the things to think a lot more... »

Answers: Arizona tornadoes

By Jack Williams ©2015

Q: Do tornadoes occur in south-west Arizona, including in the Yuma area? Chris,  Yuma, Ariz. A: A few tornadoes have occurred in Yuma County in the past, which means that they can  occur in the future. Nevertheless, the record shows they are rare and usually weak. If  you go to the National Climatic Data Center's (NCDC) Storm Events Web page, select "Arizona"... »

When seasons begin — revistited

By Jack Williams ©2015

Q: Hello Jack. I was wondering if anyone ever turned in an answer on your "official seasons" proposal from last summer. I am doing my senior research project on the seasons, and would like to know what you found out. Thank you for your time. Justin, Redwood Falls, MN [caption id="attachment_1938" align="alignleft" width="300" caption="Where it's light and dark on earth at 11:30... »

Answers: Weather balloons and airplanes

By Jack Williams ©2015

Q: Hi, I enjoyed "Rise Up" in the March 2010 AOPA Flight Training magazine.   I wonder about  the danger of those weather balloons and noted your  comments about there being "no danger" as it's floating down under parachute. But really, hasn't there ever been an incident or accident associated with one of these balloons where one of them (either... »

Answers: Storm Winds

By Jack Williams ©2015

Q: Why doesn't an extratropical cyclone continue to rotate around a 360-degree axis, like a hurricane?  I've always wondered why a cold front begins to the northwest of the low center and then dies out on the northeast side. Why doesn't it continue to just rotate?  How does the Coriolis effect play into all of this? Jeff, Pensacola, Florida A:  The answer... »

Ask Jack: Humid Air

By Jack Williams ©2015

Q: Why is humid air less dense than dry air? Matt, LaGrange, Ga. A: At first it might seem strange that humid air is actually less dense than dry air at the same temperature.  Most of the time we say things... »