00:00 - From the band family studios in the department of

00:03 - meteorology and atmospheric science at penn state

00:07 - this

00:07 - is whether world.

00:39 - The reason there weather on our planet

00:42 - is that the earth is round

00:43 - so the sun heats it unevenly

00:45 - and that sets the air in motion.

00:48 - But the earth also spins

00:50 - and this spin shapes the patterns of weather we observe

00:53 - as you now see when things are spinning it's a pretty complicated world

00:58 - and while we don't notice it here in Pennsylvania

01:00 - the earth is spinning eastward at seven hundred

01:03 - miles per hour.

01:05 - Yes the spinning earth is a dizzying place.

01:08 - From where you're now sitting

01:09 - you've just gotten a glimpse of the forces at work.

01:12 - It is apparent that it's time to consider something we call

01:16 - the coriolis force.

01:20 - If the earth were not spinning the air would flow directly from the

01:23 - Equatorial regions

01:25 - to the icy polar caps.

01:33 - However these satellite pictures from Japanese TV

01:36 - show that in the middle latitudes weather systems generally move from west to east

01:40 - this motion is a consequence of the coriolis force.

01:48 - We've come to the local playground to be able to show first hand

01:51 - just how this coriolis force works that's right this merry go round is going to

01:55 - eventually play the part of our spinning earth

01:57 - and as baseball here will be a chunk of air

02:00 - now here in this non-rotating world if i roll the ball it goes straight

02:04 - i roll it back to Fred

02:05 - also go straight Isaac Newton long ago said in his first law of motion

02:09 - an object going straight will continue going straight

02:11 - unless acted upon by a force

02:13 - that's right but if we were to set this merry go

02:15 - round rotating it would be a whole different world

02:18 - would you do the honors brought

02:19 - my pleasure for it.

02:26 - Well thanks Paul for the span and welcome aboard our private rotating world we're

02:29 - going to try this rolling the ball trick

02:31 - again

02:32 - and now we're pretty good at rolling curveballs.

02:36 - That's right Fred you can see that.

02:38 - Each time it's deflected to the right

02:40 - which is

02:41 - exactly what happens to all air motions here in the northern hemisphere

02:44 - that's right you know and it wouldn't look quite

02:47 - the same if we weren't on this merry go round

02:49 - let's take a look at how this looks from above.

02:53 - From up above the ball is and continues to go straight between us.

02:58 - Meaning that the coriolis force only needs to be considered

03:01 - for those who are rotating.

03:07 - On weather maps

03:08 - emotion of air around lows and highs

03:10 - is subject to the coriolis force

03:13 - air flowing from high to low pressure

03:15 - when deflected to the right by the coriolis force

03:18 - takes on the familiar clockwise rotation

03:20 - in this hemisphere.

03:23 - By the same token

03:24 - air moving towards the center of low pressure

03:26 - being deflected to the right in the northern hemisphere

03:29 - takes on a counter clockwise spin.

03:32 - If you've ever wrestled with one of these babies a revolving door you know that

03:36 - rotation can interfere with your emotion.

03:40 - And so too it is true of the coriolis force

03:43 - the coriolis force in the atmosphere it

03:45 - interferes with the direct transport

03:48 - of air from the equator

03:50 - to the pole

03:51 - and in so doing

03:52 - it helps give the size

03:54 - the shape

03:55 - and the intensity of weather systems we observe.

03:58 - However

03:59 - unlike in this room evolving door.

04:01 - In the atmosphere

04:03 - there is simply

04:04 - no way out.

04:06 - I

04:18 - and.

04:26 - This looks like a pretty good spot for a break and

04:29 - it has been a hot day out here pounding the pavement

04:31 - in search of still some more weather wise Pennsylvania

04:34 - how about a nice

04:35 - picnic brunch sounds great to me

04:36 - you know Fred it's so hot out here i bet you

04:38 - we could actually fry an egg on the pavement

04:41 - fried eggs for a picnic a perfect

04:43 - well let's see what we have in the basket.

04:46 - You know there's nothing quite like the fun of a picnic

04:49 - you're right Fred

04:50 - the Pam please you go.

04:53 - So we have

04:54 - salt and pepper and of course

04:56 - yeah i think we're already.

05:00 - Would you do the honor sir

05:02 - gladly.

05:05 - You know not only is this a great idea for a picnic

05:08 - it's a great idea

05:09 - for a question.

05:11 - Have you ever heard that it's hot enough to

05:13 - fry an egg

05:14 - on the pavement yup do you think that's true

05:16 - sure.

05:19 - I've tried it didn't work.

05:21 - How

05:23 - do you think it's ever hot enough.

05:25 - Fry an egg.

05:27 - On the pavement.

05:29 - I read the

05:30 - fans.

05:32 - That way.

05:34 - Yeah a time

05:35 - frame with that.

05:38 - Magnifying.

05:40 - Fries

05:41 - and.

05:42 - No

05:43 - but i think that you could probably.

05:46 - Cook

05:47 - a

05:47 - relatively

05:48 - nice cut of meat.

05:50 - I've done it you've done it

05:51 - just to

05:51 - get to find out if it's true

05:53 - gotten a hood and rash it on the hood of a car.

05:57 - It'll cook

05:57 - okay

05:58 - i'm gonna try that

05:59 - don't do it let you put some stuff on it because you hard to get on

06:02 - maybe out in California

06:04 - for example in quit.

06:07 - Or in Texas.

06:09 - It can be done in Egypt not in Sullivan county

06:12 - where naturally air conditioned.

06:14 - It sounds like the chamber of commerce.

06:18 - Yeah wherever you may try to fry an egg on a sultry summer day

06:23 - it really comes down to a matter of albedo

06:26 - albedo is a term to describe how well as surface reflects the sun's energy

06:31 - from out in space the albedo of planet earth

06:34 - is about thirty five percent.

06:36 - Meaning that a little over a third of the sunlight is reflected back to space.

06:40 - A new covering of snow or ice can reflect

06:42 - over a ninety five percent of the sun's energy

06:46 - while the lush fields and farmlands of Pennsylvania

06:49 - being much darker in color

06:50 - will only send back twenty percent of the sunlight.

06:54 - A recently paved asphalt parking lot

06:56 - has now beto of less than three eighty percent

06:59 - so it absorbs ninety seven percent of the sun's heat

07:02 - and on a truly hot day

07:04 - that's just the place to try and fry an egg.

07:37 - Looks to me like our pavement picnic is an utter failure

07:40 - Fred you're right you know we picked the hottest day in central Pennsylvania we

07:44 - picked the darkest asphalt the eggs been there

07:46 - for ten minutes and it still hasn't fried

07:48 - i'm still hungry yet

07:50 - do you have any breakfast cereal in that basket

07:52 - let's say well

07:53 - how about one oatmeal.

08:06 - And.

08:14 - Imagine if you will a place right here in

08:16 - Pennsylvania where the summers are always cool

08:19 - the winters are warm

08:21 - it never rains

08:23 - and the wind hardly ever blows where is this place

08:26 - it's in Lincoln caverns right in huntington county

08:29 - where the climate year round is always the same.

08:32 - While the weather here may not be inspiring to a meteorologist

08:35 - it does open up the field of cave meteorology.

08:39 - Certainly the study of weather underground seem strange

08:43 - but a long time caver named Fred weafer

08:46 - has combined both hobby and scientific curiosity

08:49 - into this unique interest

08:51 - during the last few years

08:52 - weafer and his associates

08:54 - have painstakingly taken measurements of temperature and humidity

08:58 - in the largest section of Virginia's biggest cave system

09:01 - the trunk channel.

09:03 - For years it's been assumed that the temperature within a cave

09:06 - reflect the average annual temperature outside

09:09 - and these studies are attempting to verify this

09:12 - and more.

09:13 - Erin wall street canyon the geology is very

09:15 - interesting oh the meteorology is rather tame

09:18 - especially when you compare it to a while.

09:22 - Unlike most caves that amateur explorers like myself might view

09:26 - the wild cave is new frontier for this boulanger

09:29 - each step reveals a world unexplored and perhaps never before seen

09:34 - by human eyes.

09:39 - The rock formations can be stunning

09:41 - yet the pathways are sometimes treacherous

09:44 - the science of cave meteorology

09:46 - involves very precise measurements of atmospheric conditions

09:50 - in unexplored caves.

09:52 - As noted by these graphs

09:54 - the weather within seldom varies

09:56 - but it's the subtle seasonal variations in addition to the sudden adjustment

10:01 - near a cave entrance

10:02 - that are the focus of cape meteorology.

10:05 - It may seem like a list of numbers to many of us

10:08 - yet these values were gathered by spending more than ten hours

10:11 - in the dark and muddy interior of a cavern.

10:15 - In only a half a dozen projects like this one

10:18 - and none as detailed or current as the Butler cave study.

10:22 - Perhaps the dedication of a few cavers

10:24 - will unlock new secrets about the way the world beneath

10:27 - us behaves certainly though the climate of most caves

10:30 - is amazingly constant.

10:35 - Penn's cave which is unlike most caves in the state

10:38 - is filled with water

10:39 - which offers a whole new dimension to this study of cave meteorology

10:43 - still

10:44 - regardless of the weather inside or out

10:46 - for most people

10:47 - caving is just a fun way

10:49 - to spend the day

10:51 - and.

10:59 - One of the world's on the road once again

11:01 - and this is our skilled audio technician with

11:04 - what we call a

11:05 - boom mic and in fact that happens to be the very subject of our discussion tonight

11:09 - yes atmospheric booms are a thunder

11:11 - yeah there's an old fleetwood Mac tune that i remember from the days of my youth that

11:15 - at thunder only happens when it's raining but that's not true

11:18 - that's wrong thunder only happy

11:19 - when there's lightning

11:20 - that's right but

11:22 - what is it exactly that causes the sound of thunder.

11:27 - Heat and cold

11:28 - mixed.

11:29 - The.

11:31 - Different air so

11:33 - cold more mayor mics are coming together.

11:36 - When they are called live in a

11:39 - heatwave

11:40 - mix together.

11:41 - That sounds of the moisture packets sitting together okay.

11:46 - What do you think makes.

11:48 - The collision of the air

11:50 - the cold and the hot air

11:52 - pollution environment.

11:54 - Just hurting.

11:57 - Game.

11:59 - Oh i dunno i always say garage rolling

12:01 - beer beer barrels up there.

12:07 - Gods angry.

12:09 - Angels are bowling.

12:11 - Well we always told the children god was moving chairs have been heaven

12:14 - getting ready.

12:16 - I know that that is angels bowling and heaven.

12:20 - Thats what i was going.

12:23 - Thor.

12:25 - Theodore who.

12:30 - The man with the hammer i don't know.

12:35 - Clouds.

12:41 - Lightning.

12:42 - Split Saturday here coming back together.

12:45 - Well

12:46 - almost like that

12:47 - lightning is hot

12:49 - it heats a small channel of air to an incredible fifty thousand degrees fahrenheit

12:54 - this heated air expands so explosively that we hear the Sonic boom of thunder.

12:58 - Now sound travels more slowly than light so

13:01 - we see lightning before we hear it's thunder

13:03 - you can figure out how far away the lightning stroke is by counting the number of

13:06 - seconds from the time you see the flash until you hear the Rumble of thunder

13:11 - for each five seconds that you count the lightning is one mile away.

13:15 - So it's not the clash of cold and hot air.

13:19 - Or clouds crashing together or even the angels

13:22 - bowling that causes the sound of thunder

13:26 - it's just rapidly expanding air from the extreme heat of lightning

13:31 - period exclamation.