H!i Today I'm going to talk to you about a really cool, or rather hot topic. We're
going to talk a little bit about urban heat islands. Now this isn't the tropical
vacation that you might have planned for, so you can throw those flip-flops out of
the question for today. Today we're going to talk about what it means to be an
urban heat island. Now you may have been out to the country. Maybe you've been to
the forest. Maybe you've been outside of a city. I'm gonna guess that there's
probably a lot fewer parking lots. lots fewer buildings, a lot less asphalt, cars,
people. You could probably run into a lot more trees or forest or farmland. So in
the city we have all these structures like those buildings and those parking
lots that all reflect (or absorb) a lot of heat from the Sun. So today we're going to do an
experiment which shows how NASA satellites measure some of that
reflected (or emitted) heat to tell us a little bit more about the difference between the
heat in a city and the heat out in the countryside - which can impact how weather
patterns in and around a city behave and also tell us a lot about how
much of the Earth is covered in developed area versus non developed areas,
which can also impact our radiation budget – which is how much radiation from
the Sun is absorbed by the Earth or reflected by the Earth, as well as how
much of the Earth reflects its own heat and gives off its own heat as well. So to
do today's experiment we are going to need an infrared thermometer just like
this. You can just order these online, maybe pick them up from a hardware store
if you have one nearby and you can go. So all we're gonna do is - it looks kind of
like a squirt gun - all you have to do is push the trigger and point at different
objects and it'll tell you the temperature on the display
on the back. So I have mine set to Fahrenheit, but you can also do degrees
Celsius as well. All right, so I've set up a bright light over here this is going
to be my sun. This is a heat lamp. Now this is one that you might use for
raising chickens or other ways that they might be used to produce heat in an area,
especially for some of those animals. But what I also have, in addition to that, is
a house plant, a few different types of rocks, some water, some wet soil ,and some
dry soil. So I was just looking for a bunch of different materials that you
might find outside because not a lot of sunlight from outside is absorbed inside.
So we're going to recreate what happens outside in nature inside our house at
home. So to do this experiment I'm going to use my infrared thermometer and
measure the heat that is being reflected (or radiated) from these different objects. So first
I'm going to start with some really dry, dry dirt. So this was sitting in
the "Sun" here, or my make-believe Sun, and I'm just going to point my thermometer
at it and see what the temperature is. Well it looks to be about 76 degrees. So
I know that my house is about 68 degrees right now so 76 degrees is quite a bit
warmer. Now what happens when I do it with the wet soil? It's about 68 degrees.
So it is actually room temperature despite having sat here in my "Sun" for a
little while. I also have a rock, a very black basalt rock here that's been
sitting there and if I measure that one... we're looking at about 73 degrees. So
this is a really dark surface. Now what happens if I measure a very light
surface rock? so put this one in my "Sun" as it's been sitting there for a little
while and measure it and this one indeed is a little bit cooler.
It's about 72 degrees so it's still warmer than the air around me because
it's in direct line with that heat from my "Sun" or my heat source
here my light, but it's still reflecting some heat but not as much as the darker
rock that's absorbing more of that heat or the dark dry soil. So this brings me
to my water. So we saw that the wet soil was a lot cooler than my dry soil. So if
I do the same experiment with my water here, my water temperature is about 68
degrees as well. So that might explain why that wet soil was about the same
temperature as my water. Maybe it has something to do with the water or the
heat capacity of water, which means how long it takes for something to change
its heat when it's put in place of a heat source like that. And then, plants. So
I have an aloe plant here, the only plant I can grow indoors because my green
thumb is not so great, I'll just go ahead and show you how this one works.
And my plant is a little warm but it's not as hot as my black rock. It was about
72 degrees, so it's definitely taking on some of the heat and reflecting some of
it but it's also creating its own method of cooling called evapotranspiration,
where the plants actually create a cooler environment around them. So out in
the country where there's lots of plants we have a cooler
weather, cooler temperatures and in the city where we have a lot of dark asphalt
or pavement, it's going to be a little bit hotter as those dark materials
absorb so much of that heat from the Sun.
So using GLOBE when GLOBE observer you can go out and measure different
temperatures in your neighborhood or on the land cover around you. One other
thing I like to do with my kids is I'll let them use my infrared thermometer and
have them run around taking temperatures of different objects themselves and
record them. We call it a heat-seeking scavenger hunt. So it's a fun way to
teach kids about how different temperatures or how different objects
have different temperatures and how they can go ahead and measure it as well. Just
kind of like a satellite would with remote sensing or a device that senses
not directly. So urban heat islands are a really cool concept, a pretty hot topic,
and I hope that you enjoyed learning a little bit about the different
temperatures of objects and how dark objects absorb heat and lighter objects
reflect heat. So that the temperatures are hotter for the darker objects and
cooler for the lighter objects and that plants actually create their own cooler
temperatures with that evapotranspiration. Go ahead and if you have
not already download the GLOBE Observer app, so that you can go ahead and take
your own land cover measurements and help map out those urban areas or those
forested areas, grasslands, and classify those different areas so that we can get
more detail about what kind of land surface and land cover is on our Earth.
So I appreciate you guys tuning in today go ahead and keep taking those
observations Thanks!