Weather

• The atmosphere


  is a thin layer of gases that surrounds the Earth .
• nitrogen makes up


  Seventy - eight per cent of the atmosphere
• oxygen


  of the atmosphere 21 per cent
• other gases ( including argon and carbon dioxide ) .


  Less then one percent
• What does the atmosphere do?


  The atmosphere insulates the Earth from extreme temperatures . It traps heat and also protects the Earth from dangerous rays from the sun .
• How thick is the earths atmosphere?

  480 km thick but most of it is within 16 km of the Earth's surface a
• The troposphere


  the lowest layer in the Earth's atmosphere . • It reaches from ground or water level up to about 17 km . • Weather and clouds occur in the troposphere . • The temperature generally decreases as the altitude increases .
• The stratosphere is the next layer .


  • It extends from 17 km to 50 km from the Earth's surface . • The ozone layer is located in the stratosphere . Some of the highest clouds can be found in the lower stratosphere .
• solar energy


  Energy from the sun
• solar radiation


  The energy that travels through space from the sun. It is transmitted in the form of light and heat
• What does the strength of solar energy depend on?

  Its strength depends on latitude and the tilt of the Earth on its axis .
• What is the earth divided into?


  northern hemisphere and the southern hemisphere
• equator


  The imaginary line seperating the earth into two halves
• lines of latitude


  The lines around the Earth that measure distance from the equator
• Where is the south pole


  The South Pole is at 90 ° south of the equator
• Where is the north pole


  the North Pole is at 90 ° north of the equator
• Why is the heat so intense at the equator?

  • The sun's rays have a shorter distance to travel to the equator so the heat is more intense here than at higher latitudes . • The sun's rays shine directly on the equator and so are concentrated on a smaller area . The rays at higher latitudes are slanted and therefore cover a larger area and are less intense
• summer


  During our summer , the northern hemisphere is tilted towards the sun . Days are long and we receive more solar radiation .
• autumn


  During our autumn , the northern hemisphere begins to tilt away from the sun . Days get shorter and temperatures drop as we receive less solar radiation .
• winter


  During our winter , the northern hemisphere is tilted away from the sun . Days are short and temperatures are low because there is little solar radiation
• spring


  During our spring , the northern hemisphere begins to tilt towards the sun again and days grow longer . Temperatures increase with more solar radiation .
• . Wind


  is the movement of air over the surface of the Earth . Winds blow from areas of high pressure to areas of low pressure .
• When air is heated


  This makes it lighter and so it rises . This creates areas of low pressure at the equator
• 30 ° north and south of the equator


  the warm air begins to cool When air is cooled it becomes heavy and sinks towards the surface of the Earth . This creates areas of high pressure .
• Trade winds


  are air movements towards the equator
• Coriolis effect


  The rotation of the Earth on its axis which makes the trade winds appear to curve towards the west , regardless of whether they are travelling to the equator from the south or north .
• doldrums


  an area of calm weather The trade winds coming from the south and the north meet near the equator . As they are heated , these converging trade winds blow upwards so there is little movement of air near the surface , and so little wind .
• westerlies


  Between 30 ° and 60 latitude the winds that move towards the poles appear to curve to the east come Prevailing westerlies in the northern hemisphere are responsible for many of the weather movements across Europe , and especially in Ireland .
• horse latitudes


  found at 30 ° north and south of the equator . They form a belt that blows . between the trade winds and the prevailing westerlies . Horse latitude winds tend to be weak and encourage clear , bright weather .
• polar easterlies


  60 ° latitude in both hemispheres easterlies form when the atmosphere over the poles cools . This cool air then sinks and spreads over the surface . As the air flows away from the poles , it is turned to the west by the Coriolis effect.
• current


  The movement of water
• Ocean currents occur due to :


  • Differences in temperature • The Earth rotating on its axis • Wind Currents can be warm or cold depending on where they flow from .
• Currents flowing from the equator

  are warm
• The Gulf Stream


  originates in the Gulf of Mexico and the warm North Atlantic Drift Weather turns north eastwards into the Atlantic Ocean , where it splits to form ( NAD ) and the cold Canary Current . The NAD flows past the west coast of Ireland where it helps to keep ports ice - free .
• Cold currents flow from areas

  in high latitudes towards the equator
• The Labrador Current


  flows south along the coast of north - east America , reduces the temperature of the ocean and many ports freeze over as a result .
• Air masses


  large moving pockets of air
• Which air mass can carry more water vapour/moisture?

  Warm air masses
• All air masses have the following characteristics


  • They are large , often stretching more than 1,500 km across the landscape and extending several kilometres into the atmosphere . The temperature , pressure and moisture are similar at any point within the air mass . • They travel across the atmosphere as a single unit
• The following air masses affect Ireland :


  Polar maritime Arctic Polar continental Tropical continental Tropical maritime