2.4 The human impact Flashcards
What is the greenhouse effect?
The green house effect is a natural process. The earth is surrounded by a thin layer of greenhouse gases which sit around the earth. Short wave radiation from the sun travels through the layer. It is re-radiated by the earth as long wave radiation (infared waves). The layer that keep that heat inside is the layer of greenhouse gases. The layer serves to regulate the Earth’s temperature - prevents it from getting too cold
What is the human enhanced greenhouse effect?
The Human Enhanced Greenhouse Effect or Global warming is caused by humans. It happens when extra gases produced by us have made the amounts of greenhouse gases in our atmosphere more concentrated. This layer therefore stops more of the long wave radiation escaping to space and remits more of it towards the earth. The planet is heated up because of this.
What are the greenhouse gases and how have we increased their concentrations?
Impacts of global warming
- Falling crop yiels
- Rising sea level
- Significant decrease in water availability
- Extensive damage to coral reefs and the ecosystems there
- Rising numbers of species facing extinction
- Rising intensity of storms, droughts, flooding and heat waves
Define urban heat island (UHI)
A city or metropolitan area that is significantly warmer than its surrounding rural areas due to human activities
Why are urban areas hotter?
- Relative lack of moisture due to the lack of vegetation and high drainage density (many sewers and drains) which removes water
- Mostly built from concrete, brick and tarma which have low albedos meaning they absorb large quantities of heat and release it by night (offsets the cooling process)
- More pollution is equivalent to more hygroscopic particles which accelerates the onset of condensation => more cloud cover, co2 and noxious flumes to trap heat
- Reduction of heat diffusion due to changes in airflow patterns as a result of urban surface roughness
