1. Weather & Climate

2. Definitions  Weather – day to day changes in the state of the atmosphere.  Climate – average weather conditions over a longer period of time – 30 years.

3. What is the Atmosphere? An atmosphere is defined as the gaseous envelope that surrounds a celestial body. Therefore, the Earth, like other planets in the solar system, has an atmosphere, which is retained by gravitational attraction and largely rotates with it.

4. Why is it important?  Weather  Driving conditions, how we dress, stocks in shops (beer in hot summer, gloves in cold winter)  Climate  Agriculture, holidays, wet seasons, hurricane season

5. What drives weather and Climate?  What weather/climatic systems is this input of heat responsible for? SW LW

6. Composition of the atmosphere Main Elements = 99% Nitrogen (N 2 ) 78% Oxygen (0 2 ) 21% Trace Elements = 1% Xenon (Xe) Argon (Ar) Ozone (O 3 ) Carbon Dioxide (CO 2 ) Nitrogen Dioxide (NO 2 ) Neon (Ne) Iodine (I) Helium (He) Carbon Monoxide (CO) Methane (CH 4 ) Ammonia (NH 3 ) Nitrous Oxide (N 2 O) Water Vapour (H 2 0)

7.  Use the double sided handout to make notes on….  Absorption  Albedo  Factors affecting the variability of incoming solar energy (9.3)  What happens to the sun’s energy (9.4)

8. Who studies the Atmosphere? Learning about different states of the atmosphere enables science to understand and predict changes on a range of scales. Meteorology is the subject that studies the chemical and physical properties of the atmosphere together with its fields of motion, mass and moisture.

9. http://www.teachersdomain.org/asse t/ess05_int_vertical/ http://www.teachersdomain.org/asse t/ess05_int_vertical/

10. Troposphere The troposphere contains about 80% of the atmosphere and is the part of the atmosphere in which we live, and make weather observations. In this layer, average temperatures decrease with height 6.4 o c/1000m, as there is less air in contact with the ground to heat up. This is known as Environmental Lapse rate (adiabatic cooling brought about by changes in temperature caused by a decrease in pressure at height). This sphere mixes vertically by convection, conduction and turbulence more than any other sphere. These vertical motions and the abundance of water vapour make it the home of all important weather phenomena. The troposphere is around 16 km high at the equator, with the temperature at the tropopause around –80 °C. At the poles, the troposphere reaches a height of around 8 km, with the temperature of the tropopause around –40 °C in summer and – 60 °C in winter. Therefore, despite the higher surface temperatures, the tropical tropopause is much cooler than at the poles at the thickness is increased – more cooling occurs.

11. The Troposphere  Where we live (all the time)  Contains 80% of the mass of the atmosphere  Is between 8-16km (5-10 mi) deep  Deeper at the equator than the poles  WHERE WEATHER HAPPENS

12. Stratosphere Temperatures in the stratosphere rise with increasing altitude (creating a temperature inversion) this is caused by concentrations on O 3 which absorbs ultraviolet radiation. This is greatest around 50 km at the edge of the stratopause. Temperatures range from –30 °C over the winter pole to +20 °C over the summer pole according to latitude and season. As well as a noticeable change in temperature, the move from the troposphere into the stratosphere is also marked by an abrupt change in the concentrations of the variable trace elements. Water vapour decreases sharply, whilst ozone concentrations increase. These strong contrasts in concentrations are a reflection of little mixing between the moist, ozone-poor troposphere and the dry, ozone-rich stratosphere. The stratosphere extends up to around 48 km above the surface, and together with the troposphere, they account for 99.9% of the Earth's atmosphere.

13. The Stratosphere  Contains the ozone layer  Where ultra-violet radiation is absorbed –This means that we are protected from harmful high-energy radiation from the sun –This also means that the stratosphere is warmer than the top of the troposphere because it has absorbed that energy

14. Mesosphere Temperatures in the mesosphere decrease rapidly as there is no water vapour, cloud, dust or ozone to absorb incoming radiation. Temperatures at the mesopause go as low as – 120 °C with very strong winds – 3000km/hr. As in the troposphere, the unstable profile means that vertical motions are not inhibited. During the summer, there is enough lifting to produce clouds in the upper mesosphere at high latitudes

15. Thermosphere The thermosphere extends upwards to altitudes of several hundred kilometres, where temperatures range from 250 o c to as high as 1,700 o c, getting warmer with increasing height. Temperature ranges depend on the degree of solar activity and as there is more atomic oxygen there (like ozone) to absorb the heat. The temperature changes between day and night (Diurnal) amount to hundreds of degrees. Above 500 km temperatures are very difficult to define. Molecules are so widely spaced that they move independently, and there is no reason why their temperatures should be the same.

16. Air Density and height

17. Earth’s Annual Heat Budget – Heating of the Atmosphere At ‘A’ the sun’s energy is more concentrated on a small land area – intense heating. At ‘B’ the sun’s energy is spread over a wider surface area – leading to less direct heating. ‘A’ ‘B’

18. Heat Budget in OUR Winter In the North in OUR Winter there is a deficit In the South in OUR Winter there is a surplus At the equator there is a surplus Of course the Earth’s heat budget is not that simple! You have to remember the effects of seasonality – the seasonal shift in the trace of the sun on the Earth’s surface during it’s orbit.

19. Heat Budget in OUR Summer In the South in OUR Summer there is a deficit In the North in OUR Summer there is a surplus At the equator there is a surplus

20. Earth’s Annual Heat Budget So over the pattern of a year the Earth’s heat budget changes with the seasons, however there is always a surplus at the equator. The uneven distribution of heating across the Earth is what drives the air to move (WIND) in an effort to redistribute the heat to areas of deficit.