Hydro-metereological Hazards Flashcards
What are hydro-meteorological hazards?
Natural processes or phenomena of atmospheric, hydrological, or oceanographic nature that may cause economic, sociocultural, or environmental loss. Natural processes and cycles that maintain ecosystems.
2 Causes of HM hazards
Climate and weather
What is weather?
Atmospheric conditions over a short period.
High pressure system
Areas of fair, settled weather
Low pressure system
Atmosphere is relatively thin. Winds blow inward towards these areas. This causes air to rise, producing wind, clouds, and condensation (rain)
Isobars
Lines on a map which connect areas with the same air pressure
Climate def.
The average weather at a location over a long period of time. Classified by temperature and precipitation.
6 Climate zones of Australia
Equatorial
Tropical
Subtropical
Arid
Grasslands
Temperate
6 factors of weather
Humidity
Precipitation
Air pressure
Temperature
Wind
Cloud Cover
Def. relief/ orographic rainfall
Formed when air if forced to cool when it rises over relief features in the landscape such as hills or mountains. As it rises, it cools, condenses and becomes rain
Why does low pressure cause rain?
Air can rise and condense into cloud cover to bring rain
Why doesn’t high pressure cause rain
Air descends towards the ground, air cannot rise and cannot condense into cloud cover
Cold front
Colder air replacing the warmer. As cold front moves, moist unstable air is usually replaced by cold, dry, stable air.
Warm front
Boundary between warm and cool air
Warm air at the surface pushes the above cool air mass, making clouds and storms.
Replaces cool dry air with warm moist air
6 Factors causing variation in climate
Latitude
Distance from sea
Altitude
Topography
Broad patterns in the ocean and atmosphere (ENSO)
What is ENSO (El Nino Southern Oscillation)?
Variation in Pacific ocean’s temperatures, air pressure and trade winds
Each phase lasts between 1 and 3 years
Measured by differences in sea level air pressure.
Differences recorded on the Southern Oscillation Index (SOI)
3 phases of ENSO
La Nina
El Nino
Neutral
La Nina
Warm water pushed west towards Australia
Strengthening of trade winds and Walker circulation
More precipitation
Flood and cyclone
El Nino
Warm water pushed east towards South America
Walker circulation breaks down
Less precipitation
Drought, bushfire
Neutral phase of ENSO
Trae winds blow east to west
Warm water pushed west towards Australia
Less extreme weather
Def. climate change
Long-term changes in average temperatures and weather patterns.
Def. global warming
Gradual increase in the overall temperature of the Earth’s atmosphere generally due to the greenhouse effect as a result of natural or human activities
4 natural processes that impact climate change
Solar variations
Volcanoes
Milankovitch theory
Albedo
Greenhouse effect
Gases such as CO2 in the atmosphere trap heat from solar radiation, creating a warm and livable atmosphere. Natural process
Enhanced greenhouse effect
Caused by human activities e.g. burning fossil fuels, which releases excessive greenhouse gases into atmosphere e.g. CO2 which trap more heat than normal