geography: Air (seventh-midterms)

Flashcards for seventh grade geography chapter Air. (P.S. it's according to CBSE curriculum).

air?

air?

air is a mixture of gases

major components of air

Nitrogen (78%): Most abundant gas. It does not support burning but is essential for plant growth.

     - Oxygen (21%): Essential for breathing and combustion (burning). All living beings need it.

     - Other Gases (1%): Includes carbon dioxide, argon, water vapor, and other gases. Carbon dioxide is important for plants during photosynthesis.

Structure of Atmosphere

(troposphere, exosphere etc.)

 The atmosphere is divided into different layers:

  - Troposphere: Closest to Earth, where weather changes (rain, wind) occur. All living beings live here.

     - Stratosphere: Contains the ozone layer, which protects Earth from harmful UV rays of the sun.

     - Mesosphere: The coldest layer where meteors burn up.

     - Thermosphere: Has thin air; the temperature rises with height. Satellites orbit here.

     - Exosphere: Outermost layer; air is very thin.

Weather

Weather: Day-to-day changes in the atmosphere, like temperature, wind, and rain. It can change quickly.

Climate

The average weather condition of a place over a long period (usually 30 years).

 Importance of Air

- Moving air is called wind.

   - Winds are caused by the uneven heating of the Earth’s surface. 

   - Breeze: Light wind.

   - Storm: Strong, fast-moving wind.

 Air Pollution

  - When harmful substances like smoke, dust, and chemicals mix with air, it causes pollution.

   - Causes of air pollution: Factories, vehicles, burning of fuels, and deforestation.

   - Effects of air pollution: Respiratory diseases, acid rain, and global warming.

Measures to Reduce Air Pollution

  - Plant more trees.

   - Reduce the use of vehicles; use public transport or cycle.

   - Avoid burning garbage and fossil fuels.

   - Use cleaner sources of energy like solar and wind.

 Water Vapor in the Atmosphere

  - Water vapor is present in the air and is essential for the water cycle.

   - It affects weather patterns, such as humidity, rainfall, and cloud formation.

   - When water vapor condenses, it forms clouds, which can lead to precipitation (rain, snow).

Carbon Dioxide in the Atmosphere

  - Carbon dioxide (CO₂) is essential for photosynthesis, where plants make food.

   - Although it makes up a small part of the atmosphere, it plays a significant role in maintaining Earth's temperature by trapping heat (the greenhouse effect).

   - Excess CO₂ from burning fossil fuels contributes to global warming.

Ozone Layer

 - The ozone layer is located in the stratosphere and protects life on Earth by absorbing harmful ultraviolet (UV) rays from the sun.

   - Ozone depletion is caused by human-made chemicals like chlorofluorocarbons (CFCs), found in some sprays, refrigerators, and air conditioners.

 Air Pressure

 - Air pressure is the force exerted by the weight of air on the Earth's surface.

   - It decreases with height. That’s why mountain climbers carry oxygen cylinders because the air is thinner at higher altitudes.

   - Changes in air pressure cause different weather patterns. High pressure usually brings clear skies, while low pressure can lead to cloudy and rainy weather.

Wind Movement

 - Air moves from high-pressure areas to low-pressure areas, creating winds.

   - Winds can be classified into:

     - Permanent Winds: Like trade winds, westerlies, and polar winds, which blow in a fixed direction throughout the year.

     - Seasonal Winds: Change direction with seasons, like monsoon winds.

     - Local Winds: Blow in a small area for a short time, like land and sea breezes.

Humidity

   - Humidity refers to the amount of water vapor in the air.

   - High humidity makes the air feel warmer and can lead to sweat not evaporating easily.

   - Low humidity can make the air feel cooler and dry out skin and plants.

Greenhouse Effect

   - The greenhouse effect is the process where gases like carbon dioxide and methane trap heat from the sun in the Earth's atmosphere, keeping the planet warm.

   - This natural process is necessary for life, but an increase in greenhouse gases leads to global warming, which causes climate change.

 Air Quality and Health

 - Poor air quality can affect health, causing problems like asthma, lung infections, and allergies.

   - Air quality is often measured by the Air Quality Index (AQI), which ranges from "Good" to "Hazardous."

Air Pollution Control

   - Governments implement laws and policies to control air pollution, such as:

     - Enforcing emission standards for factories and vehicles.

     - Promoting the use of renewable energy sources.

     - Encouraging recycling and the reduction of waste.

     - Implementing forest conservation efforts.