Weather and Climate of the Tropics

Flashcards about Weather and Climate of the Tropics

Annual mean top of atmosphere solar radiation

The average amount of solar radiation received at the top of the Earth's atmosphere annually.

Barry and Chorley, 1998

Climate

average over 30 years

Baede et al., 2018

weather

determined by the vertical structure of the atmosphere

constant changing of the atmosphere around us

Baede et al.,2018

Tropical band

A concentrated band of incoming solar radiation located in the tropical region.

Barry and Chorley, 1998

Hadley circulation

Circulation pattern in the tropics where warm air is efficiently mixed.

Barry and Chorley, 1998

Specific humidity

• Measures the amount of water vapor in air for every kg of air

• near the surface - specific humidity is high near the equator, but low over major deserts

• Barry and Chorley, 1998

Latent heat of condensation

Energy released when water vapor condenses into liquid water.

abundance of water vapour in the tropics

water vapour - source of latent heat - drives thunderstorms

Barry and Chorley, 1998

Conditional Instability

Condition where air is stable until lifted to a certain point, after which it becomes unstable.

likely to occur in warm, moist air masses

Henderson and Robinson, 1999

Convectively Available Potential Energy (CAPE)

Amount of potential energy available for convection

the more convective available potential energy the more thunderstorms

Henderson and Robinson, 1999

Thunderstorms

crucial to how we view the functioning of the atmosphere

tropical convection pumps heat and moisture away from the surface to mid upper troposphere

Henderson and Robinson, 1999

Tropical convection

They transport heat and moisture away from surface to mid-upper troposphere

Henderson and Robinson, 1999

Local minima in solar radiation

Minimum levels of solar radiation reaching the surface coincide with tropical thunderstorm hotspots

Henderson and Robinson, 1999

Hadley circulation

Model of the tropics and subtropics near the equator with a high level of heating

explanation:

• at equator have high surface heating - positive net radiation budget

• heating fuels evaporating water vapour

• warm moist air = more cape

• = more thunderstorms

Continued

• updrafts of air here

• can reach up to 30m/s - fast

Continued …

explanation:

• creates a low pressure system near surface

• trade winds travel easterly

• E —> W

• feeds equatorial trough with more water vapour

• more water vapour = more instability

Continued…

Continued…

Explanation:

• top of atmosphere - stable lid

• stratosphere - temperatures increase with height

• air flowing out of thunderstorms meet stratosphere - get field of clouds as they spread out

• air goes poleward - until it gets affected by Coriolis effect

• after this is subsides through the depth of the atmosphere

• sinking air creates subtropical anticyclones

Energy sources associated with Hadley circulation

potential energy - something higher up = more potential energy

sensible heat - stuff you can feel

net radiation - driver of system

Hadley circulation again

• convective updraft - water vapour that gets delivered to equatorial trough - condensing

• condenation - gives energy for parcels to rise during thunderstorms

• rising air = potential energy - you get long wave emission

• latent heat by condensation is warming atmosphere

• poleward upper branch - potential energy is high - get long wave emission

• subtropics - air is sinking

• potential energy is being converted by adiabatic compression

• Barry and Chorley, 1998

Warming

Adiabatic compression is the warming of air

Barry and Chorley, 1998

Energy transport by Hadley circulation

• energy transferred poleward in the tropics

• different set up to midlatitudes

• Barry and Chorley, 1998

more on energy transport

• transient eddies in midlattitdes transfer latent + sensible heat poleward

• this latent energy is moved polewards

• poleward transport of potential energy sets gradients on which transient eddies feed

• Hadley - they are moved equator ward

• Barry and Chorley, 1998

Subtropical highs

Located on the eastern sides of ocean basins

eastern side of ocean basins are colder than western sides

Barry and Chorley, 1998

Deserts

Located on the western sides of several continents

western side of continents are drier than eastern sides

Barry and Chorley, 1998

Tropical cyclones

• Derive energy from high heat content and warm sea-surface temperatures

• most damage from tropical cyclones occur close to the coast

• do not form within 5 degrees latitude of the equator

• heat source is warm sea surface temperatures

• Barry and Chorley, 1998

Future change in the tropics

• more rainfall in ascending belt of air

• subtropics will get dryer and tropics will get wetter

Garstang and Fitzjarrald, 1999