THE GASEOUS PART OF THE EARTH

THE GASEOUS PART OF THE EARTH

1. The Earth's Atmosphere

   • Composition
     • - Dust Clouds - Gases: Carbon Dioxide 0.03 % - Water Vapour: from volcanic eruptions - Oxygen: from photosynhesis  21 % - Nitrogen: 78 % Additionally: - Gases and smoke from industry, cars, heating, etc.
   • Structure
     • - Exosphere: 700 km - Thermosphere: 80 km,    -- Ionosphere: 80-550 km. Relects radio and tv waves. - Mesosphere: 50 km. - Stratosphere: 12 km. Ozone - Troposphere: 0 km
   • Function
     • Regulates Temperature.
     • Day/night differences
       •  During Day: - Earth's surface absorbs some solar radiation and heats up. - The warm surface heats the nearest layers of air. - Some radiation is reflected and escapes. - Carbon dioxide and water vapour relects some radiation back to the Earth again. During Night: - The atmosphere stops the surface heat escaping into space. - Water vapour and carbon dioxide retain heat like the glass in a greenhouse.
     • Unequal warming
       • Depends on the latitude Depends on the inclination of Sun's rays.

2. Atmospheric Pressure and Humidity

   • Pressure
     • - Is the ratio of the weight of the atmosphere to the area over which that weight is distributed. - Is a quantity - Unit: Pascal
   • Humidity
     • - Is the amount (volume) of water vapour in a specific amount of air. - Saturation point -
     • Absolute
       • Is the amount of water vapour in 1 m3 of air at a specific moment. Expressed in grams.
     • Relative
       • Is the relationship, expressed as a percentage, between the present amount of water vapour in a volume of air and that which it could contain if the volume of air were saturated.

3. Climate

   • Influenced by: - unequal warming - masses of air with different degrees of humidity Refers to the main atmospheric phenomena in a specific region that occur every year. - Depends on latitude -expressed in term of temperature and rainfall

4. Atmospheric phenomena

   • Occurs in the troposphere: Caused by the wind: - Hurricanes - Whirlwinds or dust storms - Tornadoes Related to the water vapour: - Clouds - Rain - Fog - Frost - Snow - Hail - Dew

5. Weather

   • Refers to a series of atmosphereic phenomena that occur at a specific moment in a specific place. Scientific Instruments: - Thermometer - Barometer - Rain Gauge - Hygrometer - Weather Vane - Wind Gauge

6. The Atmosphere and Living Things