Page 16 - How It Works - Book Of Amazing Answers To Curious Questions, Volume 05-15

What are

asperatus clouds?

Understand what’s behind the world’s newest cloud formation

he last time a new type of cloud offi cially classified as asperatus clouds, when ice crystals in the clouds sink, but

was officially recognised by the from the Latin word for ‘roughened’. For are too large to evaporate in the air below.
T UN’s World Meteorological this to happen, the cause of the cloud has To form an asperatus cloud, strong
Organization was in 1951, but these choppy to be identifi ed first. Although their winds then shear the underside of the

seas in the sky could be next. formation is not yet entirely understood, mammatus cloud to form undulating
After being unable to identify the clouds some experts believe they form under the waves instead of pouches. If they are

from photos sent in by sky watchers all same conditions as mammatus clouds, classified, the clouds will be included in
over the world, the Cloud Appreciation which look as though they have a series of the International Cloud Atlas, which has
Society has proposed that they should be pouches hanging below them. These occur not been published since 1975.

Why is it hotter in cities?

The effect that causes rising urban temperatures

t’s not just busy public transport of sunlight during the day. The stored
that makes city life feel sweatier energy is given off as heat, warming the
I than rural areas. On average, area by as much as 12 degrees Celsius (22
densely populated cities are one to three degrees Fahrenheit). Cities also have
degrees Celsius (1.8 to 5.4 degrees less vegetation than the countryside,
Fahrenheit) warmer than their meaning plants can’t help to cool the air
surroundings, resulting in a by using the excess heat to evaporate the
phenomenon known as the urban heat water they absorb. Use of cars and air
island effect. Dark surfaces of urban conditioning also increases
buildings and asphalt roads absorb lots temperatures in urban areas.
Dark surfaces of urban buildings
and asphalt roads absorb lots of Cities have little vegetation for evaporative
cooling to absorb the heat given off and stored © Thinkstock
sunlight during the day by dark coloured buildings and roads

16 How It Works