Is global warming real? Image: NASA Over the past two decades, the global average surface temperature has increased noticeably. This observed warming trend indicates a significant global change and is consistent with other observed changes on our planet: There is… More
How long have satellites been used to study Earth’s weather? NASA image of Explorer VII satellite, 1964 The first successful meteorological experiment conducted from a satellite was launched on Explorer VII on October 13, 1959, just over 50 years ago.… More
Numerical Weather Forecasting is younger than rock ‘n roll!! From NOAA Before 1960, the idea that a reasonably accurate two-day weather forecast could be made routinely was a pipe dream – now it’s a routine reality. In fact, it was… More
Do tides and seiches occur on lakes? Tides are changes in water level caused by the gravitational pull on water by the moon and, to a lesser extent, the sun. Tides are of interest mainly in oceans and their coastal… More
How accurate are weather forecasts? Image: NOAA In general, weather forecasts are getting better, due to improvements in computer models, observations and our understanding of atmospheric. Accuracy depends on the purpose of the forecast and how far out it extends.… More
Is there a relationship between sun spots and climate? Since the invention of the telescope in the 1600s, observers have recorded variations in the numbers of dark spots – “sunspots” – on the Sun’s surface. These variations normally follow a… More
How can we determine how far away lightning is? Make your own lightning Because of the vast differences in the speed of light and the speed of sound, the flash of lightning precedes the rumble of thunder. It takes sound… More
Is humid air “heavier” than dry air? Broadcasters of baseball games in mid-summer commonly suggest that the air on a hot, muggy night is “heavy” and that, as a consequence, the ball will not travel as far when hit. But… More
What is space weather? Space weather describes the conditions in space that affect Earth and its technological systems. Space weather storms originate from the sun and occur in space near Earth or in the atmosphere. Space weather, like weather here… More
Does a waterspout over the ocean contain fresh or salt water? Waterspout photo from NOAA Photo Library A waterspout is a whirlwind that forms over water, beneath a cumulus cloud. Before you see the waterspout, you may see a funnel… More
What are growing degree days? The Growing Degree Day, or GDD, is a heat index that can be used to predict when a crop will reach maturity. Each day’s GDD is calculated by subtracting a reference temperature, which varies with… More
What is the dewpoint temperature? Dew on evergreens, by Michael Theberge at NOAA Think of a morning when you walked on a grass lawn or through a field. Did your shoes get wet? If yes, that is because the grass… More
What is a landspout tornado? “Landspout” is slang for a tornado that, unlike most tornadoes, is not associated with the mesocyclone of a thunderstorm. The name reflects the fact that these tornadoes look “like a weak Florida Keys waterspout over… More
Crane moves radome into position during installation of radar antennae at NOAA’s National Severe Storms Laboratory in Norman, Oklahoma Photo from NOAA How does weather radar work? Radar, an acronym for RAdio Detection And Ranging, was invented during World War… More
What are the different types of thunderstorms? Thunderstorms can be classified by severity or structure. For example, the National Weather Service defines a severe thunderstorm as one that produces one or more of the following: wind gusts of at least… More