4- Write a few lines about the main environmental problems of the planet caused by industrial activity, use text and drawing or photographs. Choose tw

- Acid rain: is rain or any other from of precipitation that is unusually acidic, i.e. elevated levels of hydrogen ions (low Ph). It has harmful effects on plants, aquatic animals and infrastructure through the process of wet deposition. Acid rain is caused by emissions of compounds of carbon, nitrogen and sulfur which react with the water molecules in the atmosphere to produce acids. Governments have made efforts since the 1970´s to reduce the production of sulfuric oxides into the Earth´s atmosphere with positive results. However, it can also be caused naturally by the splitting of nitrogen compounds by the energy produced by lightning strikes, or the release of sulfur dioxide into the atmosphere by phenomena of volcano eruptions.

- Greenhouse effect and Global Warming: The greenhouse effect is caused by an atmosphere containing gasses that absorb and emit infrared radiation. Greenhouse gases trap heat within the surface- troposphere system, causing heating at the surface of the planet or moon. This mechanism is fundamentally different from that of an actual greenhouse, which works by isolating warm air inside the structure so that heat is not lost by convection. The greenhouse effect was discovered by Joseph Fourier in 1824.
Global warming, a recent warming of the Earth´s surface and lower atmosphere, is believed to be the result of an “ enhanced effect” mostly due to human- produced increases in atmospheric greenhouse gases. This human induced part is referred to as anthropogenic global warming.