transport

Air pollution: Roadside emissions sensors help Hong Kong clean its air in world first

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Carbon monoxide and nitrogen oxide pollution have fallen sharply in Hong Kong since it introduced a world-first scheme to detect and repair vehicles with the highest emissions Technology 2 February 2022 By Alice Klein A busy road in Hong Kong picturelibrary / Alamy Stock Photo Hong Kong has improved its air quality by using roadside … Read more

There’s a Hidden Mathematical ‘Law’ in The Sand Megaripples Found All Over Earth

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Wherever there is sand and an atmosphere, prevailing winds may whip the grains into undulating shapes, pleasing to the eye with their calming repetition. Certain sand waves, with wavelengths between 30 centimeters (almost 12 inches) and several meters (around 30 feet), are known as megaripples: they’re between ordinary beach ripples and full dunes in size, … Read more