*THE EARTH’S ATMOSPHERE

*The Atmosphere is a mixture of gasses that sorrounds the Earth and protects us by blocking out dangerous rays from the Sun. It is around 800 Km thick.

*Is made up of gasses in different proportions:

*78% nitrogen.*21% oxygen.*1% other gasses: argon, carbon dioxide, water vapour, ozone, etc.

*THE LAYERS OF THE ATMOSPHERE

*There are four layers:

*Troposphere*Stratosphere*Mesosphere*Thermosphere

*Troposphere:

*It is 15 Km thick.*It contains 80% of the total mass of the atmosphere.*Here is where the meteorological phenomena occur.*It gets colder with height.*Its upper limit is called Tropopause.

*Stratosphere:

*It is about 30 Km thick.*Its temperature increases with height.*The ozone layer is here: blocks UV radiation from the Sun.*Its upper limit is called stratopause.

* Evolución del Agujero de la Capa de Ozono

*Mesosphere:

*It is about 40 Km thick.*It contains clouds of ice and dust.*It gets colder with heigth.*Its upper limit is called mesopause.*It is here where meteorites desintegrate.

*Thermosphere:

*The highest and the thickest layer.*Its temperature increases to 1.000 ºC due to the X-rays and the gamma rays from the Sun.*It is here where Polar Lights appear.

*THE WEATHER

*WHAT MAKES UP THE WEATHER?

*The weather describes the state of atmospheric conditions at a certain place, over a short period of time.*Weather conditions include:

*Wind: movements of air.*Temperature: how hot or cold the air is.*Precipitations: water that falls to the ground: rain, snow and hail.*Humidity: the concentration of water vapour in the atmosphere.*Clouds: formed when air gets cold and condensates.*Atmopsheric Pressure.

*THE ATMOSPHERIC PRESSURE

*Air has weight. *The pressure it exerts on a surface is called Atmospheric Pressure.

*Where is the pressure going to be highest?

*And lowest?

*PREDICTING THE WEATHER

LOW PRESSURE AREAS

They are areas where air rises. So, there is no much air on the terrestrial surface, and the pressure it exerts is low.

*As the air rises, it gets colder, condenses, and form clouds.*These clouds will produce precipitations (bad weather).*These areas are also called Squalls.

HIGH PRESSURE AREAS

They are areas where air descends. So, there is a lot of air on the terrestrial surface, and the pressure it exerts is high.

*As the air descends, it gets hot and dry, does not condense, and does not form clouds.*So, in these areas we will findgood weather.*These areas are also called Anticyclons.

*CLIMATE

*Climate describes the weather in an area over a long period of time.

*These factors affect climate:

*Latitude: how far north or south a place is from the Equator. The Sun heats the most at the Equator, and the least at the Poles.

*Altitude: the height above the sea level. The higher a place is, the colder it will be.

*Distance from the sea: *In winter the sea releases heat, keeping coastal areas warmer.*In summer, cold sea keeps coastal areas cooler.

So, temperatures are milder in coastal areas than in inland areas.

*CLOUDS AND PRECIPITATION

*Clouds are formed when rising air cools and condenses to form liquid drops.

*Rain occurs when condensation makes large and heavy droplets which fall to Earth.

*Snow and Hail occur when the water vapour in the air freezes.

*There are different types of clouds:

-FOG: a cloud in contact with the ground.

-CUMULUS: white and puffy clouds that usually mean good weather.

*CIRRUS: thin and high clouds made of ice crystals.

*CLIMATE DIAGRAMS

*Climate diagrams summarize temperature and precipitation information for a given area.

*For one year, we represent each month on the horizontal axis.

*Temperature and precipitation are represented on the vertical axis

METEOROLOGICAL INSTRUMENTS

*Using your book, look for the correct instrument to measure these phenomena:

*The wind direction*The amount of rainfall*The temperature*The wind speed*The humidity*The atmospheric pressure

THE THERMOMETERThe thermometer is used to measure the temperature of the atmosphere.

THE PLUVIOMETER

The pluviometer is used to measure the volume of precipitation.

THE HYGROMETER The hygrometer is used to measure atmospheric humidity.Atmospheric humidity is the amount of water vapour contained in the air.

THE ANEMOMETER

The anemometer is a device which is used to measure the speed of the wind.

THE WEATHER VANE

The weather vane is a meteorological instrument we use to measure the speed of wind.

THE BAROMETER

A barometer is an instrument used to measure atmospheric pressure, that is, the pressure exerted by the air.The records of atmospheric pressure in a certain area allow us to establish which are the high pressure areas (anticyclones) and which are the low pressure areas.