key terms

• hemisphere


  a half of the earth,usually divided into northern and southern halves by the equator
• weather


  the condition of the earths atmosphere at a particular time and place.
• climate


  The average (expected) weather conditions in an area based on data collected over 30 years or more.
• troposphere


  he area of the atmosphere from the Earth's surface to a height of 10-15km in which the weather takes place
• climate zone


  divisions of the Earth's climates into belts or zones, according to average temperature and average rainfall. The three major zones are polar, temperate and tropical.
• latitude


  he imaginary lines that surround the earth ranging from 0° at the equator to 90° at the pole
• atmospheric air pressure

  The force exerted on the Earth's surface by the weight of the air, measured in millibars.
• low pressure


  caused when air is rising, so less air is pressing down on the ground; air rises as it warms, leading to low pressure at the surface.
• high pressure


  when there is more air pressing down on the ground, caused by air sinking; air descends as it cools, leading to high pressure at the surface.
• condensation


  the process by which rising water vapour becomes a liquid.
• precipitation


  he collective term for moisture that falls from the atmosphere; this could be in the form of rain, snow, sleet or hail
• hadley cell


  a system of vertical and horizontal air circulation that creates major weather patterns, predominantly in tropical and subtropical regions
• ferrel cell


  air circulation cell found at midlatitudes (between 30° and 60°) between Hadley and Polar cells.
• polar cell


  air circulation cell found between 60° and 90°, air rises at lower latitude and sinks at poles.
• front

  a boundary separating two masses of air with different densities, usually heavier cold air and lighter warm air.
• trade winds


  the prevailing pattern of easterly surface winds found in the tropics within the lower section of the Earth's atmosphere.
• prevailing wind


  the most frequent, or common, wind direction
• rain shadow


  an area or region behind a hill that has little rainfall because it is sheltered from rain bearing winds.
• monsoon


  heavy rainfall that arrives as a result of seasonal wind, notably in southern Asia and India between May and September.
• Katabatic wind


  movements of cold dense air that flow downhill and along valley floors; in Antarctica, most winds blow towards the coast from the centre.
• What climatic changes does El Niño cause?

  Unusually warm water in the Pacific
• When does El Niño typically occur?

  Late December
• What are the effects of El Niño on wind patterns?

  Reversal of wind patterns across the Pacific
• What weather conditions does El Niño cause in Australasia?

  Drought
• What weather conditions does El Niño cause in South America?

  Unseasonal heavy rain
• What is the thermocline?

  Temperature change point in water layers
• What is drought?

  Prolonged period of low rainfall
• What is La Niña?

  Colder than normal surface waters
• What defines a tropical storm?

  Wind speeds between 39-74 mph
• What causes the Coriolis effect?

  Earth's rotation on weather patterns
• What is the intertropical convergence zone (ITCZ)?

  Low-pressure belt around the Equator
• How does the ITCZ migrate?

  Between the Tropics of Cancer and Capricorn
• What is a heatwave?

  Prolonged period of abnormally hot weather
• What defines a super typhoon?

  Sustained wind speeds of at least 150 mph
• What is an emerging and developing country (EDC)?

  Country not fully economically developed
• What is primary industry?

  Economic activity collecting raw materials
• What is the inner core of the Earth?

  Solid metal core at 6000°C
• What is the outer core composed of?

  Semi-solid outer core radiating heat
• What is the mantle?

  Hot, dense liquid rock continuously moving
• What is the crust?

  Solid rocky shell layer over the mantle