weathering the storm tm 2

weather

The temporary state of the atmosphere, including temperature, precipitation, wind, and visibility. E.g. It is rainy and windy today.

• Climate

• The long-term average of weather patterns over time, typically 30+ years. E.g. Christchurch has a cool, dry climate.

tip for weather and climate

Tip: If the question says "today" or "this week" — it’s weather. If it's asking about long-term patterns — it’s climate.

Practice Questions:

• What is the difference between weather and climate? Give an example.

• Why does climate data usually cover 30 years?

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Explain why different parts of NZ and the world experience different climates

• Latitude: Distance north or south of the equator (0°). Closer = warmer.

• Altitude: Height above sea level. Higher = colder.

• Relief: Shape and height of the land. Affects how air moves and where rain falls.

• Rain shadow: A dry area on the leeward side of a mountain due to descending, warming air.

• Maritime climate: Coastal areas. Mild temps, regular rain.

• Continental climate: Inland. Hotter summers, colder winters, dry.

tips for why diff parts of nz have diff climates

Look out for:

• Place names like "Alexandra" (dry) = rain shadow.

• "Hokitika" = heavy rain from orographic rainfall.

• "Mt Cook" = altitude = colder + more rain.

Practice Questions:

• Why does Alexandra have a dry climate while Hokitika is very wet?

• How does altitude affect the climate of Mt Cook?

• Compare the climate of Auckland and Christchurch and explain why they are different.

Study how we can predict and measure the weather

• Thermometer: Measures temperature.

• Barometer: Measures air pressure in millibars (mb). Falling pressure = bad weather.

• Rain gauge: Collects and measures rainfall in mm.

• Anemometer: Measures wind speed.

• Wind vane: Shows wind direction.

Isobars:

Lines on a weather map that join areas of equal air pressure.

Close isobars = strong winds.

• Wide isobars = calm winds.

Pressure units

• : Air pressure is measured in millibars (mb).

  • Standard sea level pressure is about 1013 mb.

Pressure Systems (high)

High Pressure (Anticyclone):

• Clockwise rotation in the Southern Hemisphere.

• Clear skies, calm weather, light winds.

• Often brings settled conditions and cooler nights.

Pressure systems low

Low Pressure (Cyclone): (depression)

• Anticlockwise rotation in the Southern Hemisphere.

• Cloudy, wet, windy weather.

• Associated with fronts and storms.

Cold Front:

A cold air mass pushes under warm air.

• Brings sudden heavy rain and cooler temps.

• Often shown as a blue line with triangles.

Warm Front:

: A warm air mass slides over cooler air.

• Brings steady rain and gradual warming.

• Shown as a red line with semicircles.

Occluded Front:

• cold front catches up to warm front.

  • Mix of warm and cold air = complex and stormy.

💡 Tips for interpreting maps:

• If the map shows tight isobars and an L: expect wind and rain.

• If you see an H with spaced isobars: expect calm, clear skies.

• The wind flows along isobars, not across them.

• Wind blows clockwise around highs, and anticlockwise around lows in the Southern Hemisphere.

Exam Tricks:

• Always name pressure systems and fronts in your answers.

• Use wind direction and spacing of isobars to back up your points.

Practice Questions:

• What do tightly packed isobars indicate?

• How do you identify a cold front on a weather map, and what conditions does it bring?

• Describe the weather expected in a high-pressure system with widely spaced isobars.

Evaluate the evidence for and against climate change and study its impacts

Key Terms & Definitions:

• Climate change: Long-term shift in global or regional climate patterns, often caused by increased greenhouse gases.

• Greenhouse gases: CO₂, methane, water vapor – trap heat in atmosphere.

• Global warming: Increase in Earth’s average temperature.

• Sea-level rise: Result of melting glaciers and thermal expansion.

• IPCC: International body reviewing climate science.

Analyse the causes and effects of an extreme weather event:

• Disruptions to Infrastructure:

  Flooding, coastal erosion, and landslides can damage buildings, roads, and other critical infrastructure. 

• Agricultural Impacts:

  Droughts can reduce crop yields, while excessive rainfall can damage crops and disrupt farming practices. 

• Social Impacts:

  Extreme weather can displace communities, create food shortages, and increase the risk of disease outbreaks. 

• Economic Impacts:

  Damage to infrastructure and agriculture can lead to significant economic losses. 

• Environmental Impacts:

  Coastal erosion, changes in water levels in lakes and rivers, and alterations to ecosystems are all potential consequences of extreme weather. 

• Specific to New Zealand:

  Rising sea levels and storm surges can lead to coastal erosion, impacting coastal communities and developments. Warmer temperatures are causing snowlines to retreat further upslope and glaciers to melt. 

Key Definitions:

• Cyclone: A low-pressure system with a rotating centre, bringing intense rain and winds. In the South Pacific, they're called tropical cyclones.

• Storm surge: A rapid rise in sea level due to winds and low pressure, often flooding coastal areas.

• Tropical Cyclone Formation:

  • Needs warm sea temperatures (26.5°C+), moist air, and low wind shear.

  • Air rises rapidly, forming clouds and releasing latent heat, which fuels the storm.

El Niño

• Natural cycle that shifts weather globally. Can cause drier or wetter seasons in NZ depending on phase.

Causes of Cyclone Gabrielle:

• Warm ocean temperatures.

• Climate change (possibly increasing storm severity).

• Low-pressure centre intensified by global patterns (La Niña before it).

effects of Cyclone Gabrielle

• Flooding in Hawke’s Bay and Northland.

• Power outages, landslides, blocked roads.

• Widespread property damage.

• Emergency evacuations and disruption to infrastructure.

Practice Questions:

• Describe the formation of a tropical cyclone.

• What made Cyclone Gabrielle particularly destructive?

• Explain two effects Cyclone Gabrielle had on people and the environment.

• To what extent did climate change influence the strength of Cyclone Gabrielle?

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all key terms/vocab

• Weather: Temporary (hours to days) conditions. Focus on short term.

• Climate: Long-term trends (decades). Focus on averages.

• Latitude: Near the equator = more direct sun = hotter.

• Altitude: Higher = colder. Think of snowy mountains.

• Relief: Shape of land affects rain. Windward = wet, leeward = dry.

• Rain shadow: Caused by descending, dry air after mountains.

• Orographic Rainfall: Air rises over mountains, cools, rains.

• Frontal Rainfall: Two air masses meet. Common in NZ.

• Convectional Rainfall: Hot surface causes rising air → afternoon storms.

• Tropical zone: Near equator; hot and wet.

• Temperate zone: Mid-latitudes; seasonal.

• Polar zone: Near poles; cold and dry.

• Greenhouse Effect: Keeps Earth warm naturally, worsened by human emissions.

• Continental Climate: Inland. Big temp changes.

• Maritime Climate: Coastal. Mild and wet.

• Cyclone: Intense low-pressure system.

• El Niño: Natural event shifting weather globally.

• La Niña: Opposite of El Niño; cooler waters but more storms in NZ region.

practice Questions:

• What type of rainfall happens when warm air meets cold air?

• What is a rain shadow, and where is one found in NZ?

• How does latitude affect a region’s temperature?

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🧪 Exam Skills

Climate Graphs – Interpreting Weather Conditions

Climate Graph includes:

• Temperature = red line.

• Rainfall = blue bars.

📈 What to look for:

• Hot? Over 25°C avg

• Mild? Between 10–25°C

• Cold? Under 10°C

• Rainfall total? Under 500mm = dry. Over 1000mm = wet.

• Seasonal pattern?

  • Summer rain = tropical/convectional

  • Winter rain = frontal

  • Even rain = maritime

🔍 Tricks:

• Temp range > 10°C = continental

• Temp range < 10°C = maritime

• Highest bars = wettest month = season clue

Example Questions:

• What season does this place get the most rainfall?

• Describe the climate of this place using the graph.

• Explain why this location has high summer temps and low rainfall.

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how a cyclone is formed

1. Warm Ocean Water: Cyclones form over oceans that are at least 26.5°C to a depth of 50 meters. This warm water provides energy for the storm.

2. Evaporation and Rising Air: Warm, moist air rises from the ocean, creating a low-pressure zone near the surface.

3. Condensation and Heat Release: As the air rises, it cools and water vapor condenses into clouds. This releases latent heat, which powers the cyclone and causes more air to rise.

4. Coriolis Effect: Because of the Earth’s rotation, the rising air begins to spin. In the Southern Hemisphere, this rotation is clockwise.

5. Spiral Structure Develops: More warm air is drawn into the low-pressure centre, feeding the system and causing it to rotate faster. An "eye" forms in the centre.

6. Sustained System: The cyclone continues to grow if conditions (warm water, moist air, low wind shear) are right. When it moves over land or cold water, it weakens.

Tropical Cyclone Formation Summary:

• Warm ocean + rising moist air + Coriolis effect = cyclone.

• Eye = calm centre; Eye wall = strongest winds and rain.

Marrtimevs continetnetal climate

Maritime Climate:

• Close to the ocean.

• Small range in temperature.

• Example: Auckland

Continental Climate:

• Far from the ocean.

• Large temperature range (hot summers, cold winters).

• Example: Alexandra

Climate Change: Evidence and Impact

Evidence For Climate Change:

• Rising global average temperatures

• Melting glaciers and polar ice caps

• Rising sea levels

• Increased frequency of extreme weather events (e.g. droughts, cyclones)

Evidence Against:

• Some believe climate change is due to natural cycles (but 97% of climate scientists agree humans are the main cause).

Impacts on NZ:

• More extreme events (e.g. Cyclone Gabrielle, flooding, droughts)

• Rising sea levels threatening low-lying coastal communities

• Changing growing seasons and stress on water supplies