Week 5

the earth needs to warm in order to emit more infrared energy to space and re-establish radiative balance

w/m^2/oC determines how efficiently the earth cools to space per unit of global warming

fuelled by solar energy - it works to redistribute heat horizontally (eddy currents circulate circularly and correolis effect) and vertically (convection) • more energy is focused in the tropics and less in high latitudes therefore there is more heating in some areas

Idea that there is an uneven distribution of solar radiation = there is more heating near the equator than at the poles - the beam is spread over a larger area which decreases the flux of energy per unit of area

in the tropics the atmosphere recieves more heat than it can radiate away the excess radiative energy in the tropics is transported to higher latitudes by the circulation of the atmosphere and the ocean this varies depending on the season

Net short = net solar radiative heating net long = net infrared radiative cooling

the atmosphere but oceans are also important for energy transport

Northward is defined as postive so the transport is positive to the NH negative in the SH - but oceans also important for transport especially in the tropics the graph for this is a flipped S with a line down the middle for the southern hemisphere it is negative for the northern is it positive

The mean meridional circulation - north south eddy (turbulent) motions - spinning motion or turbulence

Air is heated from the surface, it becomes less dense than the air above it and start to rise = convection air will stop rising when it is sufficiently cooled by radiation the air has to be replenished from the surface and this created cells - due to the rotation of the earth the cells break up –> 3x per hemisphere this is further influenced by the trade winds, westerlies and polar easterlies rising air is warm, sinking air is cool - contributes to the transport of heat in the tropics to the polls

tropical cell - profound impact on the climate - important for rainfall and cloud distribution

Trade winds - equator to the west - bend in both hemispheres westerlies - west to east easterlies - east to west

The rotation of the earth deflects the waves therefore the turn in a different direction

the force that affects flow in a rotating frame of reference • we are spinning around an axis - at the poles there is a small circle at the equator it is a much bigger circle in terms of distance travelled

the velocity at which the earth’s surface rotates varies with latitude this has an impact on the atmosphere and ocean circulation this can be more noticeable in some regions compared with others due to this idea of the distance travelled in each rotation being different at the poles compared to the equator

Northern - to the right Southern- to the left there is low pressure in the middle - therefore a lack of air there and air likes to flow to low pressure therefore the air surrounding it starts to go inwards correolis force happens and the air moving to the centre will bend to the right (n)/left(s) depending on the hemisphere - therefore the air flows inwards and bends creating a spiralling motion around the area of low pressure they are counter clockwise in the north and clockwise in the south in a spinning motion

Low pressure is associated with storms - low pressure has weak descent and as it cools it causes condenssation and cloud formation high pressure has less clouds - high pressure has descent and the air is dry

They are a large source of energy transport or heat transport in the atmosphere they mix cold and warm air

the difference in temperature - warmer regions on one side and cold on the other - drives winds add the effect of rotation

belts of strong eastward winds in the mid-latitudes of each hemisphere in the upper atmosphere of about 10km • coincident with strong temperature gradients - typically warm air is in the south and cold air is in the north get their energy from the temperature difference between tropics and high latitudes

• surface winds • temperature and salinity differences - both of which control density

Density increases with decreasing temperatures and increasing salinity the densiest waters are found near the sea ice margins, very cold water and high salinity - because salt is left behind when ice forms density reduces with temperature as water increases it expands and the same mass of water takes up more volume

Dense water sinks - it is cold so cold water sinks - this is critical for the overturning of water as it mixes things

ocean circulation that transports heat from low to high latitudes on average • very complicated pattern of deep water formation and surface level warm currents Deep water formation near the poles as close to sea ice - heat is being released to the atmosphere warm waters are flowing towards the norm - heat release thus transport