Urban heat islands affect human
health and it affects energy consumption. Those two things alone are 
enough to drive worldwide interest. (Zhang) When we 
build an urban area, we're replacing the vegetated surface and also
the soil surface with this imperious surface like the 
paving material and the building material. By doing this, we're basically
warming the urban areas, and this will generate a temperature difference.
And that's what we can the urban heat island. We find out
that the urban heat island affected by several factors.
The first factor will be the surrounding ecological context.
And then will be the size of the city. When talking about size, we can
we mean both the area of the city and also the population size
of the city. And then will be the shape of the city
and also the development patterns of the city. 
(Imhoff) We used a variety of satellite data, both land surface data
from MODIS and also impervious surface data from the 
Landsat satellite. Inpervious surface data essentially tells us 
how much building material is on the land surface in order to study the urban
heat island. The urban heat island is much larger if you
convert a forested area into an urban. And this is because the urban
heat island is a relative measure. So, urban areas in forests
are much warmer than the surrounding landscape than they are in deserts
for example, because the surrounding landscape is already warm.
I think the general public should be interested in urban heat islands because of the
fact that it's where most of the people live and in the next
50 years, we're going to see 80% of the global population living in 
cities. And the urban heat island matters for 
everything from health, like asthma and heart conditions, 
to how much heating and air conditioning you need to use to 
cool or heat your living space. 
(beeping)
