Exam 5 salas

Salas

LA and Mexico City air pollution example 

• Why both cities had bad smog 

• Both cities had lots of cars, which created a lot of air pollution. 

• Both are in valleys, so polluted air gets trapped. 

• Mexico City is at a high elevation, so it gets stronger sunlight, which makes smog worse. 

How Mexico City Improved Its Air 

• They closed an oil refinery. 

• Power plants switched to cleaner natural gas. 

• They took lead out of gasoline. 

• They reduced sulfur in diesel fuel. 

• They added catalytic converters to cars and made people get emissions tests. 

• They encouraged people to use public transportation, ride-sharing, and bikes. 

Results 

• By 2010–2015, pollution dropped by over 75%. 

Problems That Still Exist 

• The cities keep spreading outward, so more people drive. 

• Many drivers spend about 3 hours a day stuck in traffic. 

• In 2016, a long period of hot, windless weather caused Mexico City’s air to get almost as bad as it used to be. 

atmosphere

is the layers of gases that envelops our planet and preforms many important functions  

Atmosphere - composition

The atmosphere is primarily made up of nitrogen (about 78%) and oxygen (about 21%). The remaining 1% consists of smaller amounts of gases such as argon, carbon dioxide, methane, and water vapor. This mixture of gases plays a crucial role in supporting life, regulating climate, and maintaining Earth’s natural cycles. Human activities are increasing concentrations of gases like carbon dioxide and methane, which can disrupt atmospheric balance and contribute to climate change. 

Atmosphere - layers

The atmosphere is divided into four main layers: the troposphere, stratosphere, mesosphere, and thermosphere. The troposphere is the lowest layer, containing the air we breathe and all weather patterns, and temperature decreases as altitude increases. Above it, the stratosphere is drier and less dense, and temperature rises with altitude because ozone absorbs solar energy. The mesosphere is colder and protects Earth by burning up many meteors. The thermosphere is the outermost layer, very thin, and becomes extremely hot due to absorption of intense solar radiation.

atmosphere -Stratospheric ozone 

Stratospheric ozone refers to the ozone layer located within the stratosphere. Ozone molecules absorb a large portion of the sun’s ultraviolet (UV) radiation, preventing most of it from reaching Earth’s surface. This protection is vital because excessive UV exposure can damage DNA in plants, animals, and humans, potentially causing diseases like skin cancer and harming ecosystems. The ozone layer also influences temperature patterns in the stratosphere, making it warmer higher up in that layer.