What is the Heat Island phenomenon?

In Yokohama City, the heat of summer is becoming increasingly severe due to the overlap of the heat island phenomenon seen in urban areas with global warming.
This page introduces the heat island phenomenon.

What is the Heat Island phenomenon?　／　Heat Island countermeasures　／　Temperature Observation in the City　／　Heat Environment Survey　／　Future forecast of city temperature

The heat island phenomenon is a phenomenon in which the temperature in urban areas is higher than in the suburbs.
If you draw a isothermal line, the high temperature looks like an island.
It is called a heat island.

※Partial processing based on "Heat Island Monitoring Report 2017 (Japan Meteorological Agency, 2018)"

The main cause of the heat island phenomenon is:
①Artificialization of surface coatings, (2) High density of urban forms, (3) Increase in exhaust heat
There are three reasons.

The pavement surfaces such as asphalt and concrete and the roof surface of buildings accumulate heat when exposed to sunlight during the summer, and warm the atmosphere.
In addition, the heat stored on the pavement surface during the day is released at night, which prevents the temperature drop at night.

※Citation: “Revised Edition of Heat Island Countermeasures Guidelines (Ministry of the Environment, 2013)”

As the surrounding buildings become denser, the wind near the ground may weaken and reduce the spread of heat.
In addition, since the sky rate is reduced, radiant cooling at night is hindered, and heat is easily accumulated.

※Citation: “Revised Edition of Heat Island Countermeasures Guidelines (Ministry of the Environment, 2013)”

Artificial waste heat generated from buildings, automobiles, factories, etc. directly warms the atmosphere.
It is one of the causes of temperature rise.

※Citation: “Revised Edition of Heat Island Countermeasures Guidelines (Ministry of the Environment, 2013)”