Weather and climate

• Climate


  Climate is the average or long-term weather conditions for a larger region. This is the result of years of research and data recording.
• Effects of Climate Change

  1.      Sea Level Rises- Warming temperatures have caused increasing ice melt in our polar regions. This has exacerbated extreme events such as storm surges, erosion and flooding.

  2.      Marine Heatwaves- cause widespread coral bleaching and reef degeneration.

  3.      Loss of Marine Biodiversity- Rising temperatures increase the risk of irreversible loss of marine and coastal ecosystems.
• Weather


  Weather is the atmospheric conditions at any one place, at any one time.
• Atmospheric Pressure


  Atmospheric pressure or barometric pressure is the pressure exerted by the weight of the air on the earth’s surface. Atmospheric pressure is measured in hectopascals (hPa). Atmospheric pressure is mapped to form isobars.
• Isobars


  Isobars are lines on a weather map that connect points of equal atmospheric pressure. They help meteorologists identify areas of high and low pressure, which are key indicators of weather patterns.
• Synoptic charts


  Synoptic charts or weather maps provide a snapshot of the weather experienced at a particular place at a certain time. They can show relating to air pressure, air masses and fronts, cloud cover, wind speed, wind direction and rainfall. This information allows us to make predictions relating to temperature, humidity, ocean conditions and the likely weather for the next few days.
• High Pressure systems


  Occurs where atmospheric pressure is greater than 1010hPa. High pressure systems are characterized by light winds, clear skies and dry weather.
• High pressure cells


  High pressure cells occur where atmospheric pressure increases towards the center of the system. The air at the center of the cell descends and moves outwards.
• High pressure Weather


  Typically, a high-pressure system will experience the following weather: Light winds, Clear skies and dry weather, Greater diurnal temperature difference (warmer days due to the sun’s rays and cooler nights due to lack of cloud cover and Frost likely in winter
• Low Pressure systems


  Low pressure systems occur with pressures of less than 1010hPa. They’re often associated with stronger winds, cloudy skies and rain. A trough is an extension of low pressure from a low-pressure system.
• Low pressure cells


  These occur where atmospheric pressure decreases towards the center of the system. The air at the center of the cell is pulled inwards and ascends. Due to the Coriolis effect, winds in low pressure cells move clockwise in the southern hemisphere and anticlockwise in the northern hemisphere.
• Weather in Low Pressure Systems


  Typically, a low pressure system will experience the following weather: Strong winds, Cloudy skies, Rain , Lower diurnal temperature range (cloud cover blocks the sun and traps heat in over night and Frost is unlikely
• Tropical cyclones


  Are a very intense low-pressure system. They generate very strong winds, produce rough seas and heavy rains. Widespread damage occurs if they make landfall (contact with land).
• Wind


  Wind is the movement of air masses (common bodies of air) from high pressure areas (highs) to low pressure areas (lows). The effect of this movement of air is to rebalance the pressure in the atmosphere
• Wind Speed and Direction

  can be observed on a synoptic chart. The closer together the isobars, the greater the difference in pressure will be. This means that the winds will be stronger. Wind can be determined as winds will travel clockwise in low pressure systems and anticlockwise in high pressure systems
• Wind indicators


  The shaft indicates the direction from which the wind is coming. The black dot is the place that is experiencing the windy conditions
• Local winds


  1. Seabreeze: During the heat of the day, air above the land warms, and becomes less dense, causing it to rise. The  air above the sea, being cooler and more dense replaces the air on the land creating a sea breeze.

  2. Land breeze: During the cool of the night, air above the sea, being warmer than that above the land, begins to rise. Cooler air moves seaward to replace the warm sea air creating a land breeze.
• Warm fronts


  A front is the leading edge of change. They are the border zone between warm and cold air. There are two types of fronts, warm and cold. Warm fronts occur when warm air is pushed into a cold air mass. These are very rare in Australia. They result in drizzle and light rain over a few days.
• Cold fronts 


  occur when cold air is pushed into a warm air mass. This forces the warm air to rise causing a number of changes: Decrease in temperature: cold air replaces warm air. Change in wind direction and sometimes speed. Build up of cumulonimbus or rain bearing clouds. Increase in humidity: corresponding to a build up of clouds.
• Type of clouds:

  1. . Cirrus (Ci)
  2. Altocumulus (Ac)
  3. Cumulus (Cu)
  4. Cirrocumulus (Cc)
  5. Stratus (St)
  6. Altostratus (As)
  7. Stratocumulus (Sc),
  8. Nimbostratus (Ns)
  9. Cumulonimbus (Cb)
• Cirrus


  Appearance: Wispy, thin, and feather-like, Altitude: High (above 20,000 feet / 6,000 meters), Weather Indication: Typically indicate fair weather but can signal a change in the weather, often appearing before a warm front or storm.
• Altocumulus (Ac)


  Appearance: White or grey clouds, usually in patches or rolls, often with a wavy appearance, Altitude: Middle (6,500 to 20,000 feet / 2,000 to 6,000 meters), Weather Indication: Can indicate unsettled weather or thunderstorms later in the day, especially in humid climates.
• Cumulus (Cu


  Appearance: Fluffy, white clouds with a flat base and rounded tops Altitude: Low to middle (1,000 to 6,000 feet / 300 to 2,000 meters), Weather Indication: Generally, indicate fair weather, but can grow into larger storm clouds (cumulonimbus) in unstable conditions.
• Cirrocumulus (Cc) 


  Appearance: Small, white patches of clouds often arranged in rows at high altitudes, Altitude: High (above 20,000 feet / 6,000 meters), Weather Indication: Usually indicate fair, but cold weather. Can be a sign of impending tropical storms or hurricanes.
• Stratus (St)


  Appearance: Uniform grey cloud layer covering the sky, resembling fog but not touching the ground, Altitude: Low (up to 6,500 feet / 2,000 meters), Weather Indication: Often bring light mist or drizzle. Indicate overcast conditions.
• Altostratus (As)


  Appearance: Gray or blue-grey clouds that usually cover the entire sky, Altitude: Middle (6,500 to 20,000 feet / 2,000 to 6,000 meters), Weather Indication: Often precede a storm with continuous rain or snow.
• Stratocumulus (Sc)


  Appearance: Low, lumpy clouds, usually grey with some patches of blue sky visible, Altitude: Low (up to 6,500 feet / 2,000 meters), Weather Indication: Can bring light rain or drizzle, generally indicate overcast but not necessarily rainy conditions.
• Nimbostratus (Ns)


  Appearance: Thick, dark clouds that cover the sky, Altitude: Low to middle (up to 10,000 feet / 3,000 meters), Weather Indication: Continuous, steady precipitation, typically associated with long-lasting rain or snow.
• Cumulonimbus (Cb)


  Appearance: Towering, dense clouds with a flat, anvil-shaped top, Altitude: Low to very high (up to 60,000 feet / 18,000 meters), Weather Indication: Indicate thunderstorms, heavy rain, lightning, hail, and tornadoes.
• Waves


  Waves are created by energy passing through water, causing it to move in a circular motion. Winds are often the main source of this energy.
• Swell


  A swell is an open ocean wave that hasn’t broken yet. Swell is created by the transfer of energy from wind into water, and the longer and stronger the wind blows, the bigger and more powerful a swell will be.
• Swell formation steps


  – Part 1: Storms and winds out at sea blow on the surface of the ocean, creating ripples. These early stages of a swell’s formation are quite unorganized

  – Part 2: A young swell will have an erratic wavelength. Over time, these non-uniform waves will merge and synchronize, making two smaller waves into one.

  – Part 3: The further a swell travel, the more chances there will be to merge. This creates larger cleaner swells, with a larger swell period. Swell period is measured by timing the interval between wave peaks in seconds.
• Seas


  'Sea' is a description of the wind waves raised by the wind and storms in the immediate vicinity of the place of observation at the time of observation. A key difference between seas and swells are that the “wind waves” are not self sustaining and will die out when the wind stops. Because these waves haven’t had to travel very far to reach the coast, they haven’t had the chance to merge. This means the wind waves associated with seas are weaker, disorganized and have a shorter period.
• Sea state


  The “sea state” is the overall combination of the seas and the swell. It is important for boaties and surfers alike to be aware of the current sea state, as it can make the difference between and fun and safe day or a dangerous and unpleasant day out on the water.
• Tropical cyclones


  A tropical cyclone is an intense low-pressure system. They form over the ocean, generating strong winds, rough seas and heavy rains. If they make landfall, they have potential to cause widespread damage.
• Cross-section of a Cyclone


  In the southern hemisphere winds associated with low pressure systems blow in a clockwise direction towards the center of the system.