ACTIVITY 1.18 Study the sketch before answering the questions set: 1. What is a heat island? 2. Desaribe how a heat island forms. 3. Name the part of the urban area (A) that records the highest day-time temp 4. State THREE factors that contribute to the high temperatures in area A 5. Suggest TWO reasons for the drop in temperature being experienced at B. 6. Comment on the unusual shape of the isotherm at C. 7. Describe tvio ways in which cily planners are designing urban centres to re island effect.

Below are suggested answers based on the information provided by the sketch and typical details about urban heat islands: 1. What is a heat island?  A heat island is an urban area where temperatures are significantly higher than those found in surrounding rural areas. This temperature difference is largely due to human activities and modifications of the natural environment that lead to increased heat absorption and reduced cooling. 2. Describe how a heat island forms.  A heat island forms when natural land surfaces (such as vegetation and soil) are replaced by built surfaces (like concrete, asphalt, and dark roofs) that absorb and retain more heat. Factors include:   • Reduced vegetation and green spaces, which normally help cool the air through evapotranspiration.   • Heat generated from vehicles, industrial processes, and air conditioning systems.   • Design features that limit airflow and increase heat storage in urban materials. 3. Name the part of urban area (A) that records the highest daytime temperature.  Based on the sketch, the central core of area A—the dense built-up region with a high concentration of buildings and paved surfaces—typically records the highest daytime temperature. 4. State THREE factors that contribute to the high temperatures in area A.  • High density of impervious surfaces (concrete, asphalt) that absorb and store heat.  • Lack of vegetation, which reduces natural cooling through evapotranspiration.  • Concentrated human activities (traffic, industrial processes, air conditioning) that release additional heat. 5. Suggest TWO reasons for the drop in temperature being experienced at B.  • The presence of green spaces or parks that provide shade and facilitate cooling through evapotranspiration.  • Nearby water bodies (such as lakes, rivers, or fountains) that have a moderating effect on local temperatures by absorbing heat and releasing moisture into the air. 6. Comment on the unusual shape of the isotherm at C.  The isotherm may have an irregular shape at C because of a localized anomaly in land use or surface conditions. For example, a large park, water feature, or an area with reflective or light-colored surfaces could create a cooling effect that distorts the typical circular pattern of increasing temperatures. This anomaly indicates that microclimatic factors are locally influencing the temperature distribution. 7. Describe two ways in which city planners are designing urban centres to reduce the heat island effect.  • Incorporating green roofs, parks, and urban forests to provide shade and increase evapotranspiration, thereby reducing ambient temperatures.  • Using reflective or “cool” building materials for roofs and pavements, which reflect more sunlight instead of absorbing it, along with designing urban layouts that promote airflow to dissipate built-up heat. These answers integrate general concepts of the urban heat island effect and likely interpretations based on the provided sketch.