Heat islands and urban domes

Air escaping from heated buildings, atmospheric particles absorbing infrared radiation at night, the reduction in wind speed, and the heat from thousands of engines combine to make the city into an island of warmth surrounded by a cool, rural "sea." It is a heat island.

During the day the temperature rises rapidly. On a sunny day in summer it may rise by as much as 31°F (17°C) between dawn and the middle of the afternoon. It falls again at night, but in the early part of the night the city center may be up to 14°F (8°C) warmer than the surrounding countryside. The effect is so strong that urban heat islands are clearly visible in satellite photographs taken in infrared light.

On clear, calm nights the difference between the temperature inside and outside the city sometimes generates country breezes. Warm air rises over the city center, producing a local area of low pressure. Air from outside the city converges on the low-pressure region, entering as a cool, light wind.

A similar breeze occurs when city air becomes trapped beneath an urban dome. This happens when warm air lies above cooler air, producing a temperature inversion above the city. Warm air rises over the city, but cannot penetrate the inversion, because air in the inversion layer is less dense than the air rising from below. Trapped beneath the inversion, the city air spreads to the sides. As it moves, the warm air loses heat by radiating it upward, so the farther it travels from the center the cooler the air becomes. Its density increases as its temperature decreases and the air subsides just outside the city boundary. It then returns to the city center as a low-level Urban dome

Lysocline Layer

breeze. This establishes a cell-like flow of air, with air converging at ground level in the city center and diverging beneath the inversion. As the illustration on page 155 shows, the warm air then forms a dome above the city.

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Responses

  • Daniel
    How heat and pollution dome change at night?
    3 years ago
  • SAVANNAH MCINTOSH
    Why the pollution dome differs between day and night?
    3 years ago
  • veijo nurmi
    How the heat and pollution dome willchange during the night?
    3 years ago
  • katlyn
    Why polution dome lower at night?
    3 years ago
  • DIRK FREUD
    How the heat a pollution dome will be change duringt the night?
    3 years ago
  • Joseph Scott
    What is the difference between an urban heat island and a pollution dome?
    3 years ago
  • kris
    Why pollution dome happen day and night?
    2 years ago
  • hilda
    Why pollution dome is common at night?
    2 years ago
  • aydin
    What is the difference between pollution domes anheat island effect?
    2 years ago
  • selassie abaalom
    What is a pollution dome and heat island combined?
    2 years ago
  • Peony
    What is the difference between heat island and a pollution domr?
    2 years ago
  • danait
    When during the day does pollution dome occurs?
    2 years ago
  • POPPY
    How pollution domes forms at night?
    1 year ago
  • kristian
    Why pollution dome forms?
    1 year ago
  • Katja
    Why pollution dome happen at night in urban areas?
    9 months ago
  • Elanor
    What is the relationship between pollution dome and urban heat island?
    9 months ago
  • virgilia
    Why a pollution dome form?
    9 months ago
  • VANESSA
    What influences the shape of pollution dome during the day?
    9 months ago
  • mandy
    What is a pollutin dome?
    8 months ago
  • Arto
    How is the pollution dome affecting people?
    7 months ago
  • sabrina
    Are urban heat islands the same as a dome?
    2 months ago
  • layton
    What creates and are the effects of an urban heat island how does a dust dome form?
    1 month ago

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