Hydroclimatology Flashcards
what’s the difference between climate and weather?
Climate- 30 year average of atmospheric information such as rainfall, temperature and pressure
Weather - shorter term variability about these average conditions
How is incoming radiation filtered by the atmosphere and earth surfaces? (3)
- reflected or absorbed by the atmosphere or earth surfaces
- reflected not involved in earths climate system (back to space)
- absorbed radiation allows conversion between energy types, heat production and exchange which drives the global climate system
Name the 2 components that reflection of incoming radiation is made up of?
Clouds
Molecules and dust/aerosols
What is the largest agent of reflection and radiation filtering in the earth system?
Clouds
+ reflecting 20% of incoming solar radiation
What is Rayleigh scattering?
When incoming radiation is reflected by water vapour, dust and air molecules
Difference between direct and diffuse radiation?
Direct - travelling in the same beam direction
Diffuse - travelling in all directions so produced less shadow
What is the difference between the wavelengths it ozone/ aerosols and water vapour?
Ozone/ aerosols - short wavelengths
Water vapour - longer wavelengths
What is ‘global’ radiation?
The sum of diffuse and direct radiation
How to calculate net shortwave radiation
Total absorbed - total reflected = net shortwave radiation
What is the ratio of radiation absorbed and reflected at the earth surface?
Absorbed 70%
Reflected 30%
Explain how the balance of outgoing longwave radiation prevents overheating?
- trapping LW radiation gives earth a warmer temperature
- loss to space prevents overheating
What is global warming?
Addition of greenhouse gases to the atmosphere, more molecules to trap outgoing long wave radiation
Difference in shortwave radiation between the tropics and the poles?
Tropics recieve more shortwave radiation than they emit
Poles emit more than received
What happens to the shortwave radiation absorbed at earths surface?
- > 50% re emitted as long wave radiation
- the rest is used to drive the surface energy balance providing linked to the hydrological cycle
What is latent heat?
Where heat is transferred to drive a phase change with no change in temperature
What is sensible heat?
Where heat transfer ones increase the temperature
Difference in the energy used from latent and sensible heat on land and water?
- latent: used to change state of water
- sensible: used to change temperature of atmosphere
What is ground heat flux energy used for on land and water?
To change the temperature of ground surface
What is net radiation used for?
Direct heat transfers e.g latent heat flux and sensible heat
How does latent heat flux link energy and water balances?
- evaporation from the ocean
- soil evaporation and transpiration from plants
Where is most of the earths heat stored?
In the oceans
How does the atmosphere remain saturated?
- evaporation increases water vapour conc in atmos
- condensation reduces it
When these two values are equal
Name 3 main types of humidity?
- absolute humidity
- relative humidity
- specific humidity
Define absolute humidity
Total amount of water vapour in the atmosphere (doesn’t take temperature into account)
Define relative humidity
The ratio of measured humidity to saturated humidity at that temperature
What is a cold front?
Cold air moving to replace warm air
Explain convection
Vertical transport of less dense noisy air higher in the atmosphere where it can cool
Describe a monsoon
Where warm moist air from the ocean meets a very warm land surface to drive very deep convection high into the atmosphere
What is the main mechanisms to make rain?
Cooling the air by forcing it higher into the atmosphere
What is precipitation recycling?
When vegetation pumps a lot of water back into atmosphere and this is reused as rainfall
Define an aerosol in climate context
suspension of fine solid particles in the air
What is the role of reflected radiation in the earth’s climate?
None, it goes back to space
Describe the albedo of water surfaces?
very low
What is specific humidity?
The mass of water vapour in a parcel of air compared to the total mass of the air parcel
The atmosphere is mostly ___ to shortwave radiation
transparent
How much of total incoming energy is reflected by the earth itself?
A small fraction
Which landscape has a higher albedo?
- bare soil and deserts
OR
- vegetation or agriculture
bare soil and deserts
What makes a good absorber?
Poor reflector
What is outgoing radiation?
the re emission of radiation if heating of a substance occurs
Why is the earths average temperature higher than what it should be?
because the atmosphere is delaying and storing the transfer of heat away from the earth
