Summary of Lecture 1

SUMMARY OF LECTURE # 1 WED 5th Sep 2012

● WELCOME & INTRODUCTION TO THE COURSE

● COURSE OUTLINE, TUTORIALS, TESTS, etc., EXPLAINED AS IN THE COURSE OUTLINE ON THE COURSE WEBSITE

● INFO GIVEN ABOUT THE COURSE WEBSITE:

www.yorku.ca/mcdade/nats1750

SUMMARY OF LECTURE # 2 FRI 7th Sep 2012 EARTH’S ATMOSPHERE EVOLVES:

● EARTH’S ATMOSPHERE IS VERY SPECIAL ● TO UNDERSTAND IT WE NEED TO LOOK AT HOW THE ATMOSPHERE EVOLVED ● HISTORY GOES BACK TO VERY 'START' OF THE UNIVERSE ● 15 BILLION YEARS AGO WE HAD THE ‘BIG BANG’ ! ! ● OVER NEXT FEW BILLION YEARS GALAXIES FORMED - OUR OWN GALAXY FORMED ABOUT 10 BILLION YEARS AGO. ● 5 BILLION YEARS AGO OUR SOLAR SYSTEM FORMED ● EARTH’S FIRST “PRIMARY” ATMOSPHERE WOULD HAVE BEEN MAINLY H2 & He ● PRIMARY ATMOSPHERE OF HOT H2 & He “BOILED-OFF” OR BLOWN AWAY BY THE ‘SOLAR WIND’ ● AS THINGS COOLED 'OUTGASING' OF SURFACE LED TO ‘SECONDARY ATMOSPHERE’ OF H2O, CO2 & N2 ● AS SECONDARY ATMOSPHERE OF H2O, CO2 & N2 COOLED THE H2O CONDENSED TO FORM OCEANS & CO2 DISSOLVED IN OCEANS TO LEAVE ‘POST-SECONDARY’ ATMOSPHERE OF MOSTLY N2 + SOME H2O AND CO2 BUT THE ATMOSPHERE TODAY IS – 78% N2, 21% O2, 1% Ar, + CO2,, H2O (VARIABLE) + OTHERS

Q. WHERE DID TODAY’S O2 COME FROM ? A. PHOTOSYNTHESIS BY EARLY GREEN PLANTS CONVERTED CO2 & H2O TO O2 & [CH2O] ● CO2 & H2O REMOVED FROM ‘POST-SECONDARY’ ATMOSPHERE AND REPLACED WITH O2

● THE CO2 WAS CONVERTED TO FOSSIL FUELS THAT WE BURN TODAY

● BURNING OF FOSSIL FUELS RETURNS MORE AND MORE OF THE CO2 BACK INTO THE ATMOSPHERE

Suggested reading for this lecture:

TL&T 13th, p. 462-467; The Atmospheric Composition, Structure and Temperature. p. 460-462; p 465-467

T&L 11th, Composition of the Atmosphere, p437-439; Box 16.2 p441; Carbon Dioxide. p 574-576 T&L 10th, p407-408; Box 15.2 p410; Carbon Dioxide. p 539-541 (9th Ed Box 14.2, p382; p509-510) SUMMARY OF LECTURE # 4 WED 12th Sep 2012

● MORE ON CHANGES IN TEMPERATURE WITH HEIGHT:

TROPOSPHERE 0 - ~10 km temperature drops turbulent & unstable T decreases by 6-10C/km – Lapse Rate Has water vapour and weather Tropopause @ 10 km

STRATOSPHERE 10 – 50 km temperature increases again stable & has ozone Ozone concentration ~10 parts per million (ppm) Stratopause @ 50 km

MESOSPHERE 50 – 90 km temperature drops again unstable & coldest place on Earth is at the Mesopause The temperature at the mesopause seems to be cooling as a result of Global Warming !! Mesopause @ 90 km

THERMOSPHERE 90 – 500 km temperature increases again Not much ‘air’ there in near space but temperature goes up to 800 or 1500 C depending on Solar Cycle (see later)

● TEMPERATURE SCALES As well as using degrees Celsius (C) we will also use degrees Kelvin (K)

The conversion from K to C is very simple but sometimes confusing ; temp in K = temp in C + 273; i.e

0 C = 273 K ; 100 C = 373 K ; 0K = -273 C

The Kelvin or ‘absolute temperature scale’ by international convention should not really have the little  in front of the K symbol – but I will keep it there for now.

Suggested reading for this lecture: TL&T 13th, Carbon Dioxide. p. 462-467; The Atmosphere Composition, Structure and Temperature. p. 460-462; p 465-467 Reading for the next few lectures: TL&T 13th, p. 668-669

‘T&L 11th, Composition of the Atmosphere, p437-439; Box 16.2 p441; Carbon Dioxide. p 574-576 T&L 10th, p407-408; Box 15.2 p410; Carbon Dioxide. p 539-541 (9th Ed Box 14.2, p382; p509-510)

SUMMARY OF LECTURE # 5 FRI 14th Sep 2012

RADIATION

I.R., VISIBLE & U.V. radiation are only small components of the entire ‘ELECTROMAGNETIC SPECTRUM OF RADIATION’ - The E.M.R.spectrum

All EMR waves have a particular wavelength , , and a particular frequency, .

All E.M.R. waves travel at the speed of light ‘c’, speed c (m/s) =  (m) x  (Hz)

1 Hz = 1 wave per second c = 300,000,000 m/s = 3x108 ms-1

The EMR that humans can see, the visible light, ranges from wavelengths of 0.4 m (blue/violet end) to 0.7 m (red end)

RADIATION CAN ALSO BE THOUGHT OF AS PARTICLES (Photons) AS WELL AS WAVES

RADIATION AS PHOTONS: THE ENERGY IS GIVEN BY

E(Joules) = h (Joules/ s-1) x  (s-1) h, “Planck’s Constant”, = 6.6x10-34 Joule s LARGER  means MORE ENERGY so SMALLER/SHORTER  also means MORE ENERGY

UV PHOTONS CARRY MUCH MORE ENERGY THAN IR PHOTONS

RADIATION LAWS - basic

1. ALL OBJECTS EMIT E.M. RADIATION 2. HOTTER OBJECTS EMIT STRONGER THAN COOLER OBJECTS 3. THE HOTTER THE OBJECT THE SHORTER THE OF ITS EMISSION – hotter objects emit at shorter wavelengths

Reading for this and the next few lectures: TL&T 13th,Spectroscopy,p. 668-669; Structure of the Sun, 678-684 ‘ ‘Radiation’ 11th T&L p449-450; 10th p. 418-419; 9th p. 390-391 ‘Study of Light’ 11th T&L p640-643; 10th p. 604-606; 9th p. 580-582

SUMMARY OF LECTURE # 6 MON 17th Sep 2012

RADIATION (continued)

RADIATION LAWS

1. ALL OBJECTS EMIT E.M. RADIATION 2. HOTTER OBJECTS EMIT STRONGER THAN COOLER OBJECTS 3. THE HOTTER THE OBJECT THE SHORTER THE OF ITS PEAK

EMISSION WHICH WILL OCCUR AT max 4. STRONG ABSORBERS OF RADIATION ARE ALSO STRONG EMITTERS, i.e strong absorbers emit more than weak absorbers

The RADIATION LAWS IN MORE DETAIL:

THE SECOND LAW is known as the “Stefan-Boltzmann Law”

B (watt m-2) = T4 with  = 5.7x10-8 watt m-2 T-4 where 1 watt = 1 Joule/s A BODY LIKE YOU AT 310 K (37C) EMITS ABOUT 500 watt m-2

THE THIRD LAW, the hotter the object the shorter the of its peak, is

“Wien’s Displacement Law”  max (m) x T (K) =3000 (m K)

Since your body temperature is about 310 K, your body radiation has a  max of about 10 m in the IR which we can’t see.

The Sun’s ‘white’ radiation peaks at  max = 0.5 m so it’s temperature is ~ 6000 K

The radiation laws control the balance that Earth makes between energy coming in from the Sun and energy Earth radiates out to space.

Reading for this and the next few lectures: TL&T 13th,Spectroscopy ,p. 668-669; Structure of the Sun, p 678-684

‘Radiation’ 11th T&L p449-450; 10th p. 418-419; 9th p. 390-391 ‘Study of Light’ 11th T&L p640-643; 10th p. 604-606; 9th p. 580-582

SUMMARY OF LECTURE # 7 WED 19th Sep 2012

No lecture – McDade missed his bus and there was a power outage in Curtis I. I am keeping this listed as Lecture #7

There was a suggestion to view: http://topdocumentaryfilms.com/the-sun/

But this viewing is for interest only

SUMMARY OF LECTURE # 8 FRI 21st Sep 2012

THE SUN

THE SUN IS A FAIRLY AVERAGE STAR – it just happens to be our closest star. Some stars are hotter but some are cooler SUN’S RADIUS IS ~ 700,000 km, i.e. about 100 times the Earth’s (7000 km) so its volume is about 1 million times the volume of the Earth

But the Sun’s density is only about 1 gm/cc as opposed to Earth’s at about 4 gm/cc – so the Sun is only about 250,000 times more massive than Earth

SUN’S STRUCTURE:

INTERIOR 0 –700,000 km T = 10,000,000 K (Core, Radiation Zone & Convective Zone) PHOTOSPHERE 300 km thin layer T = 6,000 K CHROMOSPHERE 3,000 km layer T = 4,000 K CORONA out to 1,000,000 km T = 1,000,000 K

PHOTOSPHERE exhibits GRANULES 1000 km wide; they last a few minutes CHROMOSPHERE exhibits SPICULES - extensions of the photospheric granules

At "Solar Maximum" there are more SUNSPOTS, PROMINENCES, and "SOLAR FLARES" SUNSPOTS – cooler darker regions of the photosphere which can be several thousand of km in diameter and last a few weeks. They appear to rotate with the Sun. The number observable at any time follows an 11 year cycle – The Solar Cycle PROMINENCES – large bright filaments 100,000 km high last a few days SOLAR FLARES - short episodes of increased UV, X-ray, radio emissions lasting an hour or so with stronger solar wind causing displays of the "AURORA BOREALIS" -- the "NORTHERN LIGHTS"

Suggested reading for this and the next few lectures: TL&T 13th, Structure of the Sun, p 678-684

‘The Sun’, 11th p649-655& Box 23.2 p650; 10th p.613-620 & Box 22.2, p 614 (9th p. 590-596 & Box 21.2 p 592)

For interest only, there are great images and videos at: http://soho.nascom.nasa.gov/data/realtime-images.html and http://www.auroraborealispage.net/solarmax.html and related links.

Assignment 1 for review in tutorials next week have been posted. SUMMARY OF LECTURE # 9 MON 24th Sep 2012

THE SUN – continued

The Sun's energy is generated in the Sun’s CORE where T=10,000,000 K

Nuclear fusion reactions there change 4 H nuclei (4 protons, 4p) into 1 He nucleus (two protons and two neutrons, 2p2n) with loss of mass in what is called ‘the proton-proton chain’ of nuclear reactions – analogous to a continuous Hydrogen Bomb going off. p+p+p+p (4 H nuclei ) > 2p2n (1He nucleus)

The loss of mass is converted into energy according to Einstein's E=mc2

Every second 600 million tonnes of H are converted into 596 million tonnes of He

The missing 4 million tonnes of mass each second is converted to energy to produce

3.6 x 1020 Megawatts, i.e,. about the same as 1 billion billion (1018) Pickering Ontario power plants

The Sun consumes about 2 x 1019 kg of hydrogen (H) per year

But from its radius of 700,000 km and density of 1000 kg/m3 we can estimate that it has about 1.4 x 1030 kg of hydrogen still to burn

Therefore, it could last for ~ 1.4 x 1030 / 2 x 1019 = ~ 7 x 1010 years, i.e., another more 70 billion years, if it continued at this rate.

But, sadly, it will not last that long – it will get hotter and hotter, expand, and engulf the complete solar system well before that – but not in our lifetimes.

Suggested reading for this and the next few lectures: TL&T 13th, Structure of the Sun, p 678-684

‘The Sun’, 11th p649-655& Box 23.2 p650; 10th p.613-620 & Box 22.2, p 614 (9th p. 590-596 & Box 21.2 p 592) SUMMARY OF LECTURE # 10 WED 26th Sep 2012

THE SUN – continued

The Sun radiates about 3.6 x 1026 Joules/sec (watts) into space in all directions not just toward Earth

So how much of this energy is captured by the Earth?

AMOUNT OF SOLAR ENERGY REACHING EARTH

The solar power received by one square metre of Earth is given by the TOTAL power of the Sun divided by the TOTAL AREA of an imaginary sphere at Earth’s distance from the Sun.

This is controlled by ‘The Inverse Square Law’.

Consider a 200 watt light bulb, a 1 square metre card placed 1 metre from the bulb captures 16 watts; if placed 2 metres from the bulb it only captures 4 watts; if placed 4 metres from the bulb it only captures 1 watt. i.e., double the distance quarter not half the captured power. This allows us to work out Earth’s share of the total Sun output.

Earth’s distance from Sun is 150,000,000 km. Sun’s energy at Earth is therefore spread over the area of a sphere of radius 1.5 x 1011 m.

Area of the imaginary sphere = 4R2 at Earth’s distance and this works out to be 2.8x1023 m2

3.6 x1026 watts spread over 2.8 x1023 m2 gives about 1380 watts m-2 at Earth.

This is known as “The Solar Constant” and gives the energy entering the top of the atmosphere by each square metre for an overhead Sun. The total power Earth captures from the Sun is given by the Solar Constant value multiplied by the cross sectional area of Earth which is R2 not 4R2 or 2R2.

Given that the Earth’s radius is 6,400 km it turns out that Earth (potentially) captures 1.8 x1017 watt.

If it does not want to keep heating up, Earth must radiate the same back out to space in the IR – this will establish the Earth’s Equilibrium Temperature.

Suggested reading for this and the next few lectures: TL&T 13th, Energy, Heat and Temperature, p. 472-474; The fate of Incoming Solar Radiation, p. 474-478

‘The Sun’, 11th p649-655& Box 23.2 p650; 10th p.613-620 & Box 22.2, p 614 (9th p. 590-596 & Box 21.2 p 592)

SUMMARY OF LECTURE # 11 FRI 28th Sep 2012

Earth’s magic thermostat

To balance the total energy received ‘in’ from the Sun, with a Solar Constant of 1380 watt m-2, planet Earth must radiate ‘out’ to space at an average rate of 345 watt m-2 for each square metre of its surface – averaged over day and night. The out value per square metre happens to be a quarter of the in value per square metre because – well think about it ! It receives solar energy over an effective area of R2 in but radiates out the same total amount over a larger area of 4R2. Get it ? If not contact me.

Earth sets its own ‘thermostat’ - it stabilizes its diet ! Joules (calories) in are managed to match Joules (calories) out. This allows us to calculate the expected ‘Equilibrium Temperature’ of Earth, Teq , required for this very delicate balancing act.

To radiate out at the required value of 345 watt m-2, Earth’s temperature needs to be at 279 °K (+6 °C) according to the Stefan-Boltzmann Law, E = T4, from Lecture # 6.

Therefore, we might expect the average Earth surface temperature to be 279 °K = +6 °C.

However, the average Earth surface temperature today is higher at about +15 °C . Question: Why are we wrong so far?

Answer : First thing, we forgot that some of the Sun’s radiation is reflected back to space and not really received by Earth. But if we allowed for that loss, our Teq value would be even lower and even more wrong ! The real answer is that we have ignored the Greenhouse Effect.

But to explain that we need to discuss Heat in more detail.

Mechanisms of heat transfer

HEAT is just one form of energy and like all forms of energy is measured in Joules (your food calorie is a similar energy unit just 4.2 times bigger – more on that later – that will shock you!)

HEAT is always associated with molecular or atomic motion

HEAT always moves from the hotter body to the colder body to establish an even equilibrium temperature

HEAT transfer can be by conduction – this is due to motions of individual molecules – microscopic and happens in gases, liquids and solids.

HEAT transfer can also be by convection. – this is bulk mass motion of very large collections (clouds) of molecules and only happens in gases, and liquids. Latent Heat is heat absorbed, and stored or hidden in the liquid, with no change in temperature, when a solid melts to a liquid - or when a liquid evaporates (boils) to become a gas (vapour)

Latent Heat is also the heat released in the reverse direction, when a liquid freezes to form a solid again, or when a gas (vapour) condenses to form a liquid again.

Reading for this and the next few lectures:

TL&T 13th edition, Energy, Heat and Temperature, p. 472-474; The Fate of Incoming Solar Radiation and The Greenhouse Effect, p. 474-478

Older editions;

‘Mechanisms of Heat Transfer’, 12th p 460-461 'Heat and Temperature’, 11th p 448;10th p417 (9th p 389) ‘Mechanisms for Heat Transfer’ 11th p448-449; 10th p 417-418 (9th p 389-390) ‘The Fate of Incoming Solar Radiation;12th p 462-463; ‘The Fate of Incoming Solar Radiation;11th p 450-452;10th p419-421 (9th p.391-393) 'Heating the Atmosphere: The Greenhouse Effect, 12th p 464; 11th p452-453;10th p421 (9th p393)

SUMMARY OF LECTURE # 12 MON 1st Oct 2012

Reviewed mock test 1 - sample on main page.

For specific questions feel free to contact [email protected]

SUMMARY OF LECTURE # 13 WED 3rd Oct 2012

Guest Lecturer Prof. Jim Whiteway presented a talk on “Snow on Mars” material from this will not be on the Friday 5th October test but may be on a later test/exam

FRI 5th Oct 2012 No Lecture – Test #1 MON 8th Oct 2012 No Lecture – Thanksgiving

SUMMARY OF LECTURE # 14 WED 10th Oct 2012

SUN’S HEATING OF EARTH & EQUILIBRIUM TEMPERATURE OF THE EARTH continued

THE FATE OF INCOMING SOLAR RADIATION

Not all of the in-coming solar radiation is available to heat the Earth and it's atmosphere

OF 100 UNITS IN FROM SUN:

50 absorbed by Earth’s surface & HEATS Earth (and atmosphere) 20 absorbed by atmosphere/clouds & HEATS atmosphere (and Earth) 5 reflected by surface back to space & LOST 20 reflected by clouds back to space & LOST 5 scattered by atmosphere back to space & LOST

The LOST TO SPACE component (30 units of Solar radiation in goes back out for each 100 units in at the top of the atmosphere) is called the ALBEDO and Earth’s average albedo is 30%

Because of 30% albedo, Earth’s surface would only have to radiate 241 (i.e. 0.7x345) watt m-2 in the I.R. to maintain balance with the Sun, not the 345 we used earlier!

SEE Lecture #11 Summary

Using E (watt m-2) = T4 as before but with E=241 instead of 345 now gives us T =255 K or -18 C !!

This is even colder than the observed average temperature of +15C !!

Earth is actually +15 or 16 C and not -18C because of the “GREENHOUSE EFFECT”

Reading for this and the next few lectures: TL&T 13th edition, The Fate of Incoming Solar Radiation and The Greenhouse Effect, p. 474-478

Older editions;

‘The Fate of Incoming Solar Radiation; 12th p 462-463 – this includes page numbers for the York custom 12th paperback edition ‘The Fate of Incoming Solar Radiation;11th p 450-452; 10th p419-421 (9th p.391-393) 'Heating the Atmosphere: The Greenhouse Effect, 12th p 464; 11th p452-453; 10th p421 (9th p393)

SUMMARY OF LECTURE # 15 FRI 12th Oct 2012

The Greenhouse Effect

Only 10 units of Earth’s surface I.R. radiation actually escapes to space (for each 100 units of energy IN from the Sun)

Most of the outgoing radiation is absorbed by ‘Greenhouse gases’ in the atmosphere, i.e., CO2, H2O and O3

This heats the atmosphere which then radiates some IR out to space but more back down towards the surface.

The atmosphere then sets its thermostat by emitting 60 units of Atmospheric I.R. out to space & 96 units back towards Earth’s surface. The surface then has to emit 114 units of I.R. to maintain its balance – 10 to space & 104 absorbed by the atmosphere

THE SURFACE IS BALANCED (50 sunlight in + 96 IR in from the atmosphere balanced by 20 sensible + 12 latent + 114 IR out)

THE ATMOSPHERE’S ENERGY BUDGET IS ALSO BALANCED

AND THE PLANET AS A WHOLE IS BALANCED AND IN EQUILIBRIUM WITH THE SUN !!!

See below TL&T 13th edition, The Fate of Incoming Solar Radiation and The Greenhouse Effect, p. 474-478

Older editions;

‘The Fate of Incoming Solar Radiation; 12th p 462-463 – this includes page numbers for the York custom 12th paperback edition ‘The Fate of Incoming Solar Radiation;11th p 450-452; 10th p419-421 (9th p.391-393) 'Heating the Atmosphere: The Greenhouse Effect, 12th p 464; 11th p452-453; 10th p421 (9th p393) SUMMARY OF LECTURE # 16 MON 15th Oct 2012

Spend most of today clarifying question 4 (a), Fig 1, of Assignment #1

I hope it helped it helped– and Tuesday tutorial students now have the option to submit their assignment with the Tutorial Leaders for the Thursday groups (18th October) without a late penalty – locations for those Thursday groups and times are posted on the main page.

Now back to last Friday’s stuff -

The Greenhouse Effect

Because of the “Greenhouse Effect” we now find that the Earth’s surface has to radiate 1.14 x 345 watt m-2 = 393 watt m-2 to maintain balance and equilibrium.

Now using E (393 watt m-2) = T4 leads (see Summary Lecture #11 above for procedure), this finally leads the correct expected average temperature of T = 288 K or +15 C - which is correct -- AT LAST !!

But +15 C is only the average Earth temperature. Global maps of temperature show large variations with season and latitude.

These variations are due to several effects to be discussed in next lectures.

Suggested reading this and next few lectures:

TL&T 13th edition, The Greenhouse Effect, p. 477-478; Earth-Sun Relationships, p. 467-472 Older editions; 'Heating the Atmosphere: The Greenhouse Effect, 12th p 464; 11th p452- 453; 10th p421 (9th p393); ‘Earth-Sun Relationships’, 11th p443-447; 10th p411-417 'World Distribution of Temperature', 11th p459-460; 10th p427-429 (9th p399-400)

SUMMARY OF LECTURE # 17 WED 17th Oct 2012

SUN’S HEATING OF EARTH - continued +15C is only the average Earth temperature. Global maps of temperature show large variations.

Much of the latitudinal and seasonal variations in surface temperature can be explained by the effect of the “Solar Zenith Angle” (SZA) - the angle in degrees between the vertical direction and the Sun direction.

When the Sun is overhead the SZA is 0 and the Sun’s rays are not diluted, but when the SZA is larger than 0 the Sun’s rays are diluted over a larger area and therefore cause less heating.

The SZA varies throughout the day and depends on latitude and month (i.e., season) because the Earth’s Rotation Axis (North Pole – South Pole) is tilted with respect to its orbit around the Sun by 23.5.

The North Pole points away from the Sun on December “solstice” and towards the Sun on June “solstice”

On September and March “equinoxes” the poles are not tilted with respect to the Sun – on these days there is 12 hours of sunlight everywhere

Equator has 12 hours of sunlight and 12 hours of darkness everyday but other locations (latitudes) see seasonal changes in the number of sunlit hours per day

Nevertheless, summed/averaged over a whole year all locations get the same total hours of sunlight but not the same amount of solar radiation energy

The amount of solar radiation energy received in J m-2 per day at top of atmosphere is called the “insolation”

The contour plot with Assignment 1 shows how the daily ‘insolation’ varies with latitude and season.

High latitudes show large variations in insolation throughout the year – lower latitudes (equator) show smaller variations

The contour map in Fig 2 of Assignment #1 shows the amount of radiation actually reaching the surface averaged over a year

This shows latitudinal and longitudinal structures similar to the surface mean temperature maps

Total energy received in desert regions is higher than over Amazon or oceans because of reduced cloud cover over desert regions. Suggested reading this lecture:

TL&T 13th edition, Earth-Sun Relationships, p. 467-472 Older editions; 'Heating the Atmosphere: The Greenhouse Effect, 12th p 464; 11th p452- 453; 10th p421 (9th p393); ‘Earth-Sun Relationships’, 11th p443-447; 10th p411-417 'World Distribution of Temperature', 11th p459-460; 10th p427-429 (9th p399-400)

SUMMARY OF LECTURE # 18 FRI 19th Oct 2012

SUN’S HEATING OF EARTH - continued

Although the ‘latitudinal effects’ (N-S differences) and ‘seasonal effects’ (Jan- July differences) in the global distributions of temperature (see Figs. 16.32 and 16.33 of TL&T, 13e, p.483 and similar figures in earlier editions) can be partially explained by the tilt of Earth’s rotation axis – the ‘longitudinal’ (E-W) variations at each latitude, and for each season, require more explanation. It is clear that the difference between ‘land’ and ‘ocean’ is a factor.

The explanation(s) is (are) :

(a) Water has a larger specific heat than most land materials so it takes more solar radiation to heat it up - or, in other words, water heats up less in terms of temperature increase for the same amount of solar radiation absorbed (b) The solid land is heated at its surface since the solar radiation cannot penetrate the surface – i.e., it is opaque. On the other hand water is transparent and the solar radiation is absorbed and distributed at many depths below the surface (c) Heat can be transferred, and mixed around, in the oceans by both conduction and convection but only conduction can work in the solid earth. (d) Ocean water uses a lot of its received solar energy to evaporate rather than to just increase its temperature – the land cannot do that so it heats up more rapidly.

So, on a daily basis, land heats up faster than water – and cools faster at night.

And, on a seasonal basis, land heats up faster than water as summer approaches and cools faster as winter approaches.

This is referred to as “Continentality” or “Land/Sea” effects

Much longer term solar effects and climate changes are in part caused by: Earth’s WOBBLE - ROTATION AXIS TILT DIRECTION wobbles - once every 26,000 years

Earth’s NODDING – TILT ANGLE VARIES BETWEEN 22.5 AND 24.5 degrees – once every 41,000 YEARS

CHANGES IN ORBIT SHAPE – SHAPE VARIES BETWEEN NEARLY PURELY CIRCULAR AND MOST ELLIPTICAL – EVERY 100,000 YEARS. Currently this leads to 7% variation in insolation between closest point PERIHELION and furthest point APHELION. But in about 100,000 years there will be a 20% difference.

1:15 pm FIRE ALARM !!!!!!