Weather and climate

• Weather:

  • Hourly/daily state of the atmosphere (includes temperature, sunshine, rain and wind)
• Climate:

  • Average weather of a place, describes larger areas of the world eg. desert climate
• Precipitation:

  • Any H₂O falling from the sky
• Temperature:

  • Indicates how hot or cold it is
• Wind speed:

  • Shows how fast the air is moving
• Air pressure:

  • Indicates how dense the air is (are the particles close together or far apart?)
• Cloud cover:

  • Shows the amount of clouds in the sky
• Wind direction:

  • Indicates the direction the wind comes from
• Weather is measured by meteorologists, who study the atmosphere
• In the UK, weather data is collected, processed, analysed and turned into weather forecasts by the Meteorological Office in Exeter
• Thermometer:

  • Measures temperature in degrees celsius
• Rain gauge:

  • Measures the amount of rainfall in mm by catching rain in a measuring cylinder
  • Also measures all other forms of precipitation
  • Should be placed in an open space away from trees and buildings to prevent inaccurate results
• Wind vane/wind sock:

  • Measures wind direction by pointing towards North, East, South, or West
• Anemometer:

  • Measures wind speed in mph
  • The wind speed is shown on a dial, just like a car's speedometer
• Barometer:

  • Measures changes in air pressure
  • Air pressure falls when there will be rain and rises when it is sunny
• Sunshine recorder:

  • Directs sunlight onto a card treated with a special chemical to record sunlight
• Weather instruments can be found in weather stations on land
• Water cycle:

  • Water is continuously recycled in the Earth’s atmosphere
  • Evaporation, condensation, cloud formation, and precipitation are part of the water cycle
• 3 main types of rainfall:

  • Convectional, relief, and frontal
  • All occur due to warm air rising
• Air pressure is due to the weight of all the air above us
• High air pressure is associated with sinking air and clear skies

  Low air pressure is associated with rising air, clouds, and rain
• High pressure (anticyclone) usually means settled weather with sun and few clouds

  Low pressure (depression) usually means unsettled weather with rain or snow and strong winds
• Factors affecting climate:

  • Latitude, altitude, ocean currents, prevailing wind direction, and distance from the sea
• Climate graphs show the average amount of rainfall and temperature for all 12 months of the year
• The UK’s weather is variable due to different air masses moving over the country at different times of the year
• The British Isles are located at the meeting point of air from many parts of the world
• Relief rainfall is created when warm, moist air is forced to rise over a hill or a mountain. As this air rises, it begins to cool and then condense, forming clouds. Eventually these cloud produce rainfall on the windward side of the mountain. The rain stops when the air sinks back down over the leeward side of the mountain. In the UK we get lots of relief rainfall on the high land on the west coast.
• The third type of rainfall is frontal rainfall. This is formed when a warm air mass meets a cold air mass, this creates a front. As the warm air and cold air mass cannot mix the warm air rises over the cold air. As the warm air rises it cools, and condenses, creating clouds which lead to rain. This rainfall is most common type of rain which we get in the UK.
• There are three types of rainfall: frontal, convectional and relief rainfall. In all three situations, rainfall occurs because air rises. Air contains water vapour and as the air rises it cools and condensation can occur.This means that the water vapour returns back into minute droplets of water and falls as rain. However, the air rises for different reasons.