Understanding Earth's Atmosphere and Weather Patterns

The Ozone Layer and UV Protection

Ozone is a form of oxygen. It is mainly found in the ozone layer. Ozone absorbs ultraviolet radiation; only some of it reaches the Earth. This is good because ultraviolet radiation is harmful. Chlorofluorocarbons (CFCs) were destroying the ozone. The "hole" in the ozone layer isn't really a hole, but rather there is too little ozone.

Properties of Air and Atmospheric Pressure

Air is matter; it has mass and weight. Atmospheric pressure is the weight of the atmosphere on the Earth.

• Everything on Earth is subject to atmospheric pressure.
• We do not notice atmospheric pressure because we have adapted to it and it is equal in all directions.

Pressure is a quantity that can be measured.

Humidity and Water Vapour

Air contains water vapour because of evaporation from seas and oceans, and transpiration from plants through leaves. Humidity is the amount of water vapour in a specific amount of air depending on the place, the time of the day, and the temperature (hot air contains more water vapour than cold air). Saturated air is air that cannot contain any more water vapour. The saturation point is the maximum amount of water vapour that a unit of air volume can contain without condensation occurring; it is specific to a certain temperature.

Measuring Water Content

To find the amount of water, we use two measures:

• Absolute humidity: The amount of water in 1m³ of air at a specific moment.
• Relative humidity: 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 air were saturated.

Climate and Regional Atmospheric Patterns

Climate refers to the main atmospheric phenomena in a specific region that occur every year. It is influenced by the unequal warming of the planet and large air masses with different degrees of temperature and humidity and their interaction. It depends on latitude and how near or far it is from the sea; it is expressed in terms of temperature and rainfall.

Atmospheric Phenomena in the Troposphere

Atmospheric phenomena occur in the troposphere and produce changes in the weather. They are caused by the wind, which consists of air masses in movement due to the unequal warming of the Earth's surface. Examples include:

• Hurricanes: Violent tropical storms over the ocean reaching speeds of 200 km/h.
• Dust storms: Occur on sunny days in dry, open spaces.
• Tornadoes: Inverted cone-shaped storms reaching 480 km/h.

Water Vapour and Precipitation

Atmospheric phenomena related to water vapour include:

• Due to condensation:
  • Clouds: Water vapour that condenses.
  • Fog: Low clouds.
  • Frost: Water vapour that freezes.
  • Dew: Occurs during the night.
• Precipitation:
  • Rain: Droplets in a cloud join together.
  • Snow: Occurs when the temperature inside a cloud is 0ºC.
  • Hail: Rising air currents inside the cloud freeze the water droplets.

Defining Weather Conditions

The weather refers to a series of atmospheric phenomena that occur at a specific moment in a specific place. It is described in terms of sun, rain, maximum or minimum temperatures, clouds, wind, and fronts.