Lecture 3 Flashcards
What happens to H2O for it to become a solid?
Temperature lowers and the molecules move slower
What’s the process that makes a solid a gas?
Sublimation
What’s the process that turns gas to a solid?
Deposition
What is latent heat?
Energy transferred between phase changes
What is latent heat transfer?
The amount of heat energy needed to change the state of a substance without affecting its temperature. When ice changes to water, heat energy is taken in (absorbed) for the melting and evaporating processes to occur and when water vapour condenses, the process will release latent heat energy.
Evaporation is when…
Solar energy transforms liquid into vapour
Transpiration is…
Moisture given up by plants (form of vapour)
Condensation is when…
Vapour reverts back to liquid (form of droplets)
The atmospheric system is what percentage of water?
0.0001%
The land is what percentage of water?
2.999%
97% oceanic
What does humidity describe?
The amount of water vapour in the air
What does Dalton’s law of partial pressure state?
The total sum of air pressure inside the parcel is equal to the sum of pressures of the individual gases
What is vapour pressure?
Describes the partial air pressure due to the water vapour contents in the air parcel
Relative humidity is…
Ratio of amount of water vapour actually in the air to the maximum amount of water vapour required for saturation at that particular temperature
Vapour pressure is measured in?
Mb = millibars
What is a dew point?
Represents the temperature to which air would’ve been cooled for saturation to occur.
Warm dew points indicate moist air close to saturation
Cold dew points indicate dry air.
Where does the meridonal (across latitudes) variation of relative humidity show high values?
The moist-warm tropical regions and the cold high latitude regions
Low relative humidity values can be found at…
30 degrees north and south at the location of large deserts
Warming of the air via central heating reduces relative humidity to as low as a few %. This can cause:
- Indoor plants = higher evapotranspiration
- Irritations of human skin due to moisture evaporation
- Mucous membranes in respiratory system suffer dryness: incubation of bacteria leads to infections.
Air that comes into contact with cold surfaces cools by…
Conduction
When the dew point is below 0 degrees Celsius, water vapour deposits as…
Frost
Fog forms by:
Cooling
Evaporation and Mixing
Fog occurs when condensation occurs below …
1km
Name the 3 types of fog
Radiation - cooling through night time radiation and ground conduction
Advection - warm moist air moving over a cold surface
Evaporation (mixing) - warm moist air moves with cold dry air resulting in saturation
What are the 4 modes of cloud formation?
Convection
Lifting along topography
Convergence of air
Lifting along weather fronts
What is a cloud?
A Visible aggregate of tiny water droplets/ice crystals suspended in the air
Cloud types
High e.g. Cirrus
Middle e.g. Altocumulus
Low e.g. Stratus
Vertical development e.g. Cumulus
What is water (H2O) a good absorber of?
Infrared radiation
What type of clouds do rain droplets form in when they form by coalescence?
Liquid water clouds
Raindrops will only reach a certain size before becoming…
Unstable
What is the Bergeron-Findeisen Mechanism?
It’s where the saturation water pressure is lower than over liquid water. This leads to a situation where net evaporation from liquid water droplets at the same time as net deposition onto ice crystals.
Mixed clouds (water + ice particles) –> ice crystals + hailstones, will grow at the expense of water droplets
Hailstones grow until their weight overcomes cloud up drafts.
Causes of climate change (4)
Changes in;
Plate tectonics
Earths orbit
Suns strength
Anthropogenic - combustion of fossil fuels and land use change
Internal responses of climate change
Changes in; Atmosphere Ice Vegetation Land surface Ocean
