Dirty Snow

Dirty Snow

Dirty snow melts quicker than clean snow.

share Share

At least as far back as King David’s psalms and Isaiah’s prophecies, the snow has been characterized as a symbol of purity. “Lawn [linen] as white as the driven snow” was how Shakespeare once described it.

Beyond the symbolism, the purity of snow has consequences for society. Snow is a key source of water for drinking and irrigation. It is also Earth’s best method for reflecting sunlight back into space.

Tom Painter is very interested in the purity of snow. Based at NASA’s Jet Propulsion Laboratory and the University of California, Los Angeles, he studies how much water is stored in snowpack and how that snow looks to satellites. He also studies the effects of light-absorbing impurities—dark-colored particles like dust and soot that coat snow.

Dirty snow usually melts faster than fresh snow because it absorbs more energy from the Sun, and that’s not just a problem in sooty, gritty cities. Except for some mountains and high plateaus, snow cover naturally retreats from Earth’s surface in the spring and early summer. Dust on top of that snow significantly accelerates the process.

Average Falling Asleep Time

The average person falls asleep between 10-20 minutes.

Read More
How Often Lightning Strikes?

Lightning strikes the Earth 6,000 times every minute.

Read More
Lifetime Sleep

An average person will spend 26 years asleep.

Read More
Visit of Halley's Comet

Halley's comet passes the Earth every 76 years (the next time it will return will be 2062).

Read More