Category Archives: Meteorology

Why is the grass wet in the morning, when it didn’t rain?

Recent spring mornings have produced wet lawns. To explain this, we start with the fact that air contains water in the gas phase, called water vapor. Dew is made of liquid water that has condensed from some of the water vapor in the air.

Dew occurs when objects cool. A common example of dew formation is when drops of liquid form on the glass of an ice-cold drink. Dew forms when the object, such as the glass, cools down to the dew point temperature. Continue reading

Category: Meteorology, Phenomena

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What are the plant hardy zones and how do they relate to climate?

If you are involved with gardening, you probably are aware of the hardy zones listed on seed packets.

Southern Wisconsin is largely in zones 5a and 4b, while northern Wisconsin lies in zones 3a to 4a. Continue reading

Category: Climate, Meteorology, Seasons

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When does tornado season start?

Wisconsin has had tornadoes in every month of the year except February.

We can have tornadoes almost anytime, although the chances of having one in winter are pretty small. Continue reading

Category: Meteorology, Seasons, Severe Weather

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Is there a “State Tournament Snowstorm” legacy?

A persistent anecdotal piece of weather lore around Madison is that the WIAA’s boys state basketball tournament is always accompanied by a snowstorm.

With the help of Edward Hopkins at the State Climatologist’s Office, we looked into this perception with cold, hard data. Continue reading

Category: Meteorology, Seasons

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Is carbon dioxide a major contributor to global warming?

The Earth’s atmosphere is a mixture of many different gases. Several of these gases are known as “greenhouse gases” because they share the characteristic of being excellent absorbers of infra-red radiation.

Such gases absorb radiation emitted by the Earth that would otherwise escape to space and cool the planet. Upon being absorbed, these gases re-emit a fraction of that energy back downward to the surface, keeping the planet warmer than it would otherwise be. In fact, our Earth would have an average temperature of about zero without these greenhouse gases. Continue reading

Category: Climate, Meteorology

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