Wärmeinsel: Straßenquerschnitt (3D)
About this app
Ein Schnitt durch eine Innenstadtstraße an einem Hitzetag: Asphalt, Fassaden, Baum und Wiese im Tageslauf. Man sieht, wo die Sonnenenergie bleibt — zurückgestrahlt, gespeichert, verdunstet — und warum die Altstadt nachts nicht abkühlt.
With explain mode: an AI tutor walks you through the app, points out what matters in the scene and answers your questions.
What an urban heat island is
Every surface reflects part of the sunlight, its albedo. It absorbs the rest: this heats the surface and the air, is stored in the material or is used up by evaporating water. Dark asphalt reflects only 5–10 %, grass about 25 %, light render about 60 %. Sealed surfaces and house walls release the stored heat at night. In narrow streets it escapes slowly. That is why city centres are often several degrees warmer than the surroundings at night.
What the app shows
A 3D cross-section of an old-town street on a hot day: houses, pavement, roadway, green strip and the ground below. Sun rays fall in as beams, reflected light is as strong as the albedo. The cross-section glows where heat is stored. Water vapour rises over grass and trees. A curve compares the air in the street with a park on the edge of town. All numbers are model values for understanding, not measurements.
What you can try
Swap dark asphalt for a light surface, paving or grass pavers, give the facades a light or dark render and plant street trees. Let the day run and switch on the thermal view. At 3 pm a person in the shade of a tree feels about 10 °C less, although the air is only 1 °C cooler. At night the asphalt keeps glowing in the cross-section, the grass does not.
Frequently asked questions
- Does a street tree cool the air?
- Barely: under the crown the air is usually only 1–2 °C cooler. The big effect is the shade. Surfaces and people receive no direct radiation, so the felt temperature drops by about 10 °C.
- What is a tropical night?
- A night in which the air temperature does not fall below 20 °C. It happens more often in densely built city centres, because asphalt and walls release heat at night that they stored during the day.
- What does albedo mean?
- The share of sunlight a surface reflects. Dark asphalt is at 5–10 %, light asphalt at 25–35 %, grass at about 25 %, light render at about 60 %.
- Does the app show real measurements?
- No. It runs a simple model with orders of magnitude from the literature, such as TU Munich and Schwaab et al. 2021. It is for understanding, not for planning a specific street.
Subject: Stadtklima & Klimaanpassung
More from Stadtklima & Klimaanpassung
- Asphalt raus: Entsiegelung Innenstadt (3D)
- Maßnahmenkarte kühle Innenstadt (3D)
- Platz für Bäume: Altstadt Reutlingen (3D)
- Schattenatlas Altstadt Reutlingen (3D)
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