A gray morning hangs over the lab, and the forecast on the wall screen says "wintry mix."
"Mix of what?" Rocket asks. "Rain and snow? Sleet? All of it?"
Raven checks the temperature reading. "Thirty-three degrees here, colder up the hill. What do you notice?"
"Rain down here," Rocket says. "Maybe sleet or freezing rain up there."
Nova dims the screen and brings up a map of the school route. "Which part of the trip would be icy?" she asks. "Plan for that part."
Rocket reaches for his boots. "Freezing rain is the sneaky one," he says. "It looks like plain wet pavement until you step on it."
A forecast that says rain, snow, sleet or freezing rain is telling you how to plan your day.
Freezing rain creates a coating of ice on roads, walkways, trees and power lines. Walking and driving get slippery fast.
Sleet makes moisture on roads freeze and become slippery too, but it bounces instead of coating.
Hail is a thunderstorm hazard. Hail one inch across or larger means the storm is severe, and the safest place is indoors.
Heavy rain can overflow gutters and streams. Water that is moving is stronger than it looks, so stay out of it.
Weather observers measure snow in two ways. They measure its depth on a grassy surface a short distance from the gauge.
Then they melt the snow that fell into the gauge to find out how much water it holds.
Fluffy snow holds much less water than the same depth of rain, so both numbers matter.
| Week review | True or false? |
|---|---|
| Precipitation includes rain, snow, sleet, freezing rain and hail. | ? |
| Freezing rain freezes before it lands. | ? |
| Hail grows when updrafts carry drops up into cold air. | ? |
| A good rain gauge is wider at the top than at the bottom. | ? |
| Observers read rain to the hundredth of an inch. | ? |
Next week you meet the air masses that bring all this weather, and you learn why a forecast says "chance of rain."
Excellent week, observer. Tomorrow is Station Day: a family precipitation hunt.