Why does snow melt faster on the sidewalk than it does on grass?
Imagine it has been a snowy few days and you’re looking out the window with a look of amazement at the beauty that is snowfall with a hot cup of tea in your hand..
And then you notice that there seems to be less snow on the sidewalk than there is on the grass and it makes you wonder why that is.
One of the obvious reasons could be that the city cleaned it up. Duh! They’ve been trying to up their game and have been diligently working to clean up the streets and sidewalks.
But, that does not really make a lot of sense. Why would they do that if it is still snowing. The cleaned sidewalk will be covered by a new layer of snow almost immediately.
Or, you think you friendly, helpful neighbour must have sprinkled some salt on the sidewalk so that the snow melts and it is easier for pedestrians to walk.
But then how is the entire length of the sidewalk clean? Hmmm. Surely he didn’t sprinkle the salt over the entire sidewalk!?
Here’s a scientific answer to the question.
The sidewalk is most commonly made up of concrete and well, the grass is made up of.. grass and soil.
Concrete has a higher density than grass. Density of a substance means its weight per unit volume or, simply put, the compactness of that substance. So if you took a certain weight of iron and the same measure of water, you will notice that iron occupies less than water does. This is because the density of water is less than iron’s.
Higher density also means the substance has higher conductive capacity. So, concrete is a better conductor of heat or the lack of it thereof than grass.
One of the other factors is that concrete also has greater thermal capacity than grass meaning it is able to retain more heat than grass can and takes longer for lose heat.
Grass on the other hand is, more often than not, unevenly spread. The soil depending on its quality can be more aerated or less. Thus, contributing to less heat conduction and exposure of less surface area for the snow to fall on and melt.
Now you know why snow melts faster on the sidewalk than it does on grass.
Common Science is a science blog to answer questions about everyday things that we all think about but don’t always take the time to ruminate on. I am going to answer one such question every week. Follow along if you’d like to learn some common science ;)
I hope you enjoyed this post. If you have a question you’d like me to answer in one of the posts, please feel free to comment on this article and I will make sure to answer it soon. Ciao for now!
