UK Weather and Climate Factors

Weather and Climate Definitions

• Weather: The day-to-day condition of the atmosphere.
• Climate: The average weather for a place over 30 years.

Microclimates

• Microclimates: Changes in climate over a small area (e.g., woodland, lake).

Factors Creating Microclimates:

• Buildings:
  • Reduce wind speeds (act as barriers).
  • Absorb heat.
  • Create the urban heat island effect in cities.
• Lakes: Cool down surrounding areas.
• Trees:
  • Provide shade, reducing temperatures underneath.
  • Act as wind barriers on their leeward side.
• Dark Surfaces: Tarmac roads absorb heat, raising temperatures in nearby areas. Lighter surfaces reflect heat and are cooler.

Latitude

• The north of the UK is cooler than the south. This is because the concentration of solar radiation reduces when moving away from the Equator, creating cooler temperatures.

Altitude

• Temperatures decrease 1°C for every 200 meters increase in elevation.
• Altitude affects precipitation: air forced to rise over a mountain will condense, form clouds, and rain in mountainous areas (relief rainfall).

Ocean Currents

• The North Atlantic Drift (Gulf Stream) brings warm water to the west coast of the UK, causing milder winter temperatures.

Continentality

• Places near the sea have maritime climates (sea cools summer temperatures and warms winter temperatures due to slower heating/cooling of the sea).
• Places inland have continental climates (land heats up quickly in summer and cools down quickly in winter).
• Most of the UK experiences a maritime climate due to being an island.

Weather Systems

• The UK experiences two types of weather systems:
  • High Pressure (Anticyclones)
  • Low Pressure (Depressions)

High Pressure (Anticyclones)

• Bring stable air conditions with little cloud or rain.
• In winter: clear skies, frosts, and fog.
• In summer: hot temperatures, sometimes leading to droughts that often end with convectional rainfall and thunder.

Low Pressure (Depressions)

• Move eastward from the Atlantic across the UK.
• Bring frontal rainfall (warm, tropical, maritime air mass is forced to rise over cold polar maritime air mass).
• Also bring strong winds.

Convectional Rainfall

• Warm surfaces heat up the air above. The heated air rises, cools with height, forming large clouds, and often results in heavy rain.