Weather Q&A

[Zula]

So heres my geography question for any weather fundies out there.

 

 

 

Whilst riding yesterday, my riding partner said that when the sun comes out its going to drop a few degrees for a while, and then it will get better. I thought he was smoking his socks coz how can it get cooler when the sun comes out right???? Wrong, I went from a semi defrosted state to completely numb and frozen (again).

 

 

 

Later that day I spoke to a friend of mine who is a runner and he said that its 100% true, but he could'nt give me answer.

 

 

 

Just for the record the was no cloud cover at all when it was dark.

 

 

 

Anyone know the answer??

[flex]

No idea what the reason is but I agree after experiencing this on yesterday's ride.

[Mudsimus]

When the sun sets the earth starts to cool, this continues right through the night. At sunrise it normal reaches its coldest point. The sun only starts to heat the earth when its at a 10 to 15 degree angle with the horizon.

[Capricorn]

+1 with Mud Dee. It's always coldest as the sun rises. Incident rays from the sun initially run tangential to the earth's surface, thus effectively only heating up mountains and the air. Once it hits the ground, it warms that, as well as the air due to reflection from the ground.

So when it's cloudy during the evening after the sun has set, the mornings arent that cold as the clouds reflective quite a bit of the heat being radiated from the ground.

[L.T.G]

often wondered about that too...thanks.

[Guest Big H]

The only reason why it is the coldest when the sun rises is that it is exactly that time when that portion of earth has been WITHOUT the warming rays of the sun.

 

Also go and read here.......

 

http://wiki.answers.com/Q/The_minimum_temperature_usually_occurs_near_sunrise_because

 

 

 

[Christopher Brunsdon]

 

Well I remember back from my geography at school (27 yrs back) that its at 15 minutes before sunrise that its at its coldest.

 

EDIT: After reading the WikiAnswer article I will say its depends on the time of the year. Lets keep this thread relative to Winter in the Southern Hemisphere.

 

And no, the earths orbit is not at its furthest during our Winter, it has do with the tilt of the axis, the angle of the suns rays hitting the earths surface which translats into travelling more through the earths atmosphere - which abosorbs a lot of the sun rays energy.

 

BTW: Have an UNISA Astronomy AST-131 book for sale

 

cbrunsdon2009-07-19 10:21:57

[Guest Big H]

Well I remember back from my geography at school (27 yrs back) that its at 15 minutes before sunrise that its at its coldest.

EDIT: After reading the WikiAnswer article I will say its depends on the time of the year. Lets keep this thread relative to Winter in the Southern Hemisphere.

And no' date=' the earths orbit is not at its furthest during our Winter, it has do with the tilt of the axis, the angle of the suns rays hitting the earths surface which translats into travelling more through the earths atmosphere - which abosorbs a lot of the sun rays energy.

BTW: Have an UNISA Astronomy AST-131 book for sale
[/quote']

 

Smirfman.... read the first part of my reply again and you will have your answer. The reason why it cools down further is linked to my reply. It is the longest that portion where you eare has been WITHOUT sun...... and then the sun's inability to further warm earth because of the "invalshoek". If night was another hour longer it would have cooled down even more..... unnerstand?????

[Christopher Brunsdon]

 

Well I remember back from my geography at school (27 yrs back) that its at 15 minutes before sunrise that its at its coldest.

 

EDIT: After reading the WikiAnswer article I will say its depends on the time of the year. Lets keep this thread relative to Winter in the Southern Hemisphere.

 

And no' date=' the earths orbit is not at its furthest during our Winter, it has do with the tilt of the axis, the angle of the suns rays hitting the earths surface which translats into travelling more through the earths atmosphere - which abosorbs a lot of the sun rays energy.

 

BTW: Have an UNISA Astronomy AST-131 book for sale

[/quote']

 

Smirfman.... read the first part of my reply again and you will have your answer. The reason why it cools down further is linked to my reply. It is the longest that portion where you eare has been WITHOUT sun...... and then the sun's inability to further warm earth because of the "invalshoek". If night was another hour longer it would have cooled down even more..... unnerstand?????

 

Did not quiet agree with the article but I found another one that gave me the information that was missing from the original.

 

Could ask Cassie to get hold of the exact minute after sunrise when the net radiation is 0%