Todays question

[Wolfie]

the sun heats up the earth

the sun is high in the sky

heat rises

so why is a mountain top colder than the ground below??????

 

[Jaws]

Heat is transmitted molecule to molecule.. at sea level the air is thicker hence molecules closer togther hence heat spreads and is held.. Higher up, thinner air heat can escape back out to space(ish)

Its a bit asking saying why is the space between Earth and the Sun not hot !

 

[Wolfie]

no fun jaws you are not meant to get the answer that quick!!!! :bang: :beer:

 

[D.S.]

this got anything to do with tyre pressures then? :f :}

 

[BraXX]

heat transmission

All i remember is that there are two kinds of heat transmission one is irradiation an the other is.... (forgot)
So thats why if you touch an iron bar thats heated on the other extreme (bikes cans) ya'll burn the finger, otherwise you can get the cheeks pretty close to heated bar and still not get burnt.
This is because irradiation goes throu the air but the other kind of heat transmission doesn't.
So the ground on high altitudes will absorb heat and should be warm as ground down below, same with the skin.
As i go to altitudes whilst flying hang gliders all i know is that to every 100 meters higher, you get one less degree celcius aprox.. All this cold 8ree! is worth as you ge more "confortably numb..' :-: with the sensation
Sorry i didn't meam to make it more confuse

 

[Wolfie]

41 joe, but only for left side, then 87 for the rightside.

 

[Duck n Dive]

41 joe, but only for left side, then 87 for the rightside.

You're car must be interesting to drive......

Unless of course you're always going around mountains clockwise and need the higher pressures on the right to keep the tyre temps up on that side due to the higher altitude on the right compared to the left .....

:neenaw:

 

[Wolfie]

that is on my bike!!!!!

i have these dual compound tyres, they are one tyre split down the middle by a dividing wall, you can get soft compound on the right or the left, depends which one you want.

rightsoft is a bit rare due to the roundabouts we have in this country

 

[AV8TOR]

Heat is transmitted molecule to molecule.. at sea level the air is thicker hence molecules closer togther hence heat spreads and is held.. Higher up, thinner air heat can escape back out to space(ish)

Its a bit asking saying why is the space between Earth and the Sun not hot !

Not even close try again :neenaw:

 

[Bikerbaby]

All i remember is that there are two kinds of heat transmission one is irradiation an the other is.... (forgot)

radiation
conduction
and
convection

i think thats 3 not 2

 

[BraXX]

Thank you BB so i see my numbness is not only due to altitude c7u8

 

[Jaws]

Not even close try again :neenaw:

Well it was a wild guess !!

Now come on, spill the beans then !

 

[derek kelly]

Light travels from the sun through space (which cannot store heat) enters the atmosphere or hits the ground and is converted to heat, so the nearer the ground the warmer it is.

 

[AV8TOR]

Well it was a wild guess !!

Now come on, spill the beans then !

OK try this, Contrary to popular belief the atmosphere is not heated directly by the sun. The sun heats the earth and the earth heats the atmosphere on the principal of a radiator.

This fact is made more apparent when one realises that the higher one goes the colder it becomes - in other words, one is colder on moving away from the radiator.

The seasons play a part in the amount of heat put into the radiator. In summer, British Isles, the sun is high in the sky and the days are long. In winter, the sun is at a low angle and the days are shorter. Naturally, the longer the sunshine each day, the hotter becomes the 'radiator'.

Clouds act as an insulator - it can reduce the amount of heat taken in and it can also reduce the amount that radiates or escapes into the atmosphere at night.

We could continue and explain lapse rates and the effects Adiabatic-cooling and dry and saturated lapse rates have on the atmosphere and temperature, before we even discuss nuclei transfer rate, hope that has answered your question .

 

[derek kelly]

But I was right, heat travels to earth in the form of light and on striking the Earth (radiator) turns to heat.

 

[R2B2]

OK try this, Contrary to popular belief the atmosphere is not heated directly by the sun. The sun heats the earth and the earth heats the atmosphere on the principal of a radiator.

Correct. That's reradiation you're talking about. This explains it:

The sun emits energy as electromagnetic radiation. Unlike sound, such radiation requires no medium, therefore this energy is able to travel through the near vacuum of space from the sun to the earth.

Most radiant energy from the sun is concentrated in the visible and near-visible parts of the EM spectrum, and it peaks at about 500 nm, very near the 555 nm visibility peak for Homo sapiens, a result which surely is not a coincidence (and is connected to evolution). Less than 1% of solar radiation is emitted as X-rays, gamma rays, and radio waves.

Only about 25%, or about 350 W/m2, of incoming solar radiation penetrates the transparent atmosphere of the earth. The remainder is either absorbed by the atmosphere or scattered back into space. There are some latitudinal differences found on Earth. These variations are determined by time of year, by the wavelength of the energy being transmitted, and by the depth and nature of the intervening material.

Terrestrial radiation is produced mainly as a result of reradiation of solar radiation. The energy is absorbed from the sun as the sun?s spectrum but reradiated from Earth at the much longer wavelengths associated with the temperature of Earth. The Wien displacement law, in which the wavelength is inversely proportional to the absolute temperature, provides a comparison of those peak wavelengths.

Since the sun has a surface temperature 20 times greater than that of Earth, the reradiated energy has a spectrum that peaks at a wavelength 20 times longer than the 500 nm for the sun, or at about 10,000 nm, well into the infrared. Since the atmosphere is more absorptive to such long-wavelength terrestrial radiation, the atmosphere is heated from the ground up instead of vice versa.

In addition, water vapor and carbon dioxide absorb the long wavelengths of radiation from the earth especially well, leading to the so-called "greenhouse" effect. (The temperature in real greenhouses rises mainly because the glass prevents the heated air from rising, thereby increasing the temperature inside.) Ozone, on the other hand, absorbs only very short wavelengths, mainly in the ultraviolet range, and therefore forms a shield of sorts, absorbing much of the ultraviolet radiation before it can reach the earth.

Radiation from the sun follows an inverse square law, so that comparisons of the solar constant can be made for other planets if we know their mean distances from the sun in AU. For example, Mars is 1.93 times further from the sun than is Earth. Its solar constant should therefore be about 27% that of Earth, about 374 W/m2. Because there is little atmosphere to absorb the energy, this is about the same as what we receive at the surface of Earth.

Spacecraft have provided us with temperature measurements for both Mars and Venus. Mars has an average temperature of about 5 oC, whereas Venus has a temperature of about 500 oC. Earth is about 1.4 times further away from the sun than is Venus, and we would expect from the inverse square law that it would receive about twice as much radiation. The fact that its temperature is so much greater can be attributed only to greenhouse warming.

Winter and summer seasons on Earth are a consequence not just of the obliquity factor associated with the sun?s rays, but also of the longer days during the summer than during the winter. Of course, both of these factors are a consequence of the 23.5 degree tilt of Earth?s axis of rotation with the plane of its orbit about the sun.

The sun?s radiation travels at the speed of light, and all wavelengths travel at that speed in a vacuum. When there is dispersion, some wavelengths travel at slightly different speeds than others. That is how we are able to form a spectrum with a glass prism, since blue light slows down in glass slightly more than does red light.

The methods of heat transferCconduction, radiation, and convection (advection)Callow heat to be transferred and to ultimately warm the earth?s atmosphere. Convection is particularly important to air heating and consequent movements in the atmosphere.

A balance is maintained between incoming solar radiation and the amount of terrestrial radiation. This is usually referred to as the heat budget. If this balance is disrupted, Earth will become progressively colder or warmer.

The inverse square law can be used to find the total energy per second emitted by the sun, and we can compare that number to how much energy per kilogram we would get from chemical burning. We can show that whatever is happening on the sun, it is not chemical burning. Other considerations are the constancy of the sun?s spectral lines and its mass over the span of human existence. Thus, we must explore the source of the sun?s energy, which is nuclear in its origins. This leads to a consideration of nuclear fusion, which requires an understanding of nuclear theory and special relativity (Einstein?s energy equation).

 

[AV8TOR]

Sorry I have no responce to that.
Sorry Wolfie but I think R2B2 has delivered the killer blow to this tread :} :}

 

[Jaws]

Noooo.. Not so Kenny.
A point raised by Rob is worth looking at in more detail..

Green house effect.....

Listening to a mathmatics chappy a couple of days ago and he came up with a very interesting fact..

For every human being on the planet there is estimated to be SEVEN TONS of insects ( and he went on to say that is a conservative estimate and used to ensure figures coming from that base info are not exagerated ).

So what you ask..
The what is that all those insects produce greenhouse gases.. In fact the human input to greenhouse gas even with all our fossil fuel burning ways, is less than 5% of the total emmited by all creatures on earth.

Oh and another chap in the dicsussion group came up with another interesting item which I have not seen mentioned elsewhere..

There are now split camps as to the origins of oil.

Apparently it is now equally likely we are not running out of oil, but rather, we are 'running into' it !

Some scientists now believe that due to XXXXXXXXX ( sorry, missed this bit of info ) oil is being produced all the time.