Week 10, Extreme Weather Flashcards
Weather
- Meteorological conditions including temperature, precipitation, and wind that exist in a given time and place.
- Short term
- Localized
Climate
- Meteorological conditions including temperature, precipitation, and wind that characteristically prevail in a particular region.
- Long term
- Regional
- Weather averaged over time
What is the difference between weather and climate?
Climate is the statistics of weather, they are related, but not the same.
Weather can change because of
- meteorological conditions
- daily heating/cooling
- seasonal variations
- climate changes
How do plate tectonics affect climate change?
They affect ocean circulation, bringing warm or cold water around the globe, this can have a profound impact on climate.
Natural causes of climate change:
Plate tectonics
Variations in solar heating/sun spots
Variations in Earth’s orbital properties (Milankovitch cycles)
How do variations in Earth’s orbital properties affect climate change?
Eccentricity: Cycles are elliptical, being farther from the sun means less solar heating and this was responsible for the ice ages.
Tilt: A greater tilt means greater seasonal changes, 24.5-21 degrees.
Wobble: The Earth is not uniform, this causes wobble.
Greenhouse Gases
- Climate is affected by greenhouse gases
- Certain gases within the Earth’s atmosphere trap heat.
- Solar radiation is short wavelength, heats land and oceans.
- Heated objects radiate energy at long wavelengths (infrared radiation)
- Greenhouse gases in atmosphere absorb outgoing infrared radiation as heat, preventing loss to space.
Anthropogenic Global Warming
In addition to natural climate variability, global warming is caused by anthropogenic sources of greenhouse gases:
- CO2 from burning fossil fuels
- CH4 from vegetation decomposition in absence of O2
- N20 from chemical fertilizers and automobile combustion
- O3 from automotive industrial gases (smog)
- CFC2 from coolants
Global climate change means more severe weather events and more frequent weather events, how is this possible?
Uneven heating causes extreme temperature difference between continents and oceans, this causes extreme weather.
Droughts
- A long period of abnormally low rainfall, especially one that adversely affects growing or living conditions
- Commonly caused by entrenched high pressure ridge
- Descending warm dry air desiccates land; high pressure ridge blocks inflow of moist air.
Why are heatwaves less of a concern nowadays?
Better awareness and access to air conditioning reduces hazard
Thunderstorms Early Stage:
As hot moist air rises it gets cold so we start getting clouds, water vapour condenses to liquid droplets, forms a cloud column. Condensation releases latent heat, the steam stores a lot of energy causing more air mass to uplift.
Thunderstorms Mature Stage:
Droplets and/or ice crystals become heavy enough to precipitate, causing cold downdrafts.
Updrafts and downdrafts happen side by side.
Causes gusty winds, rain, hail, and lightning.
Thunderstorms Dissipating Stage:
Downdrafts drag in surrounding cool, dry air, overwhelms warm updrafts, thunderclouds evaporate into surrounding air.
