Physical Geography Questions (AS OCR A)

I've got my exam on friday, and I'm still so stuck on Atmospheres!
Can anyone help me with a couple of quick questions?
1. What is Sensible Heat Transfer?
2. How is a Depression Formed?
and 3. What is the Adiabatic Lapse Rates all about?

I'm starting to panic as I only started revising yesterday, and I have French tomorrow which I havn't even looked at! :frown:

Reply 1

Cliffy Biro

foxylady

Hope this helps.

Sensible heat transfer is when warm air moves in to an area, it will warm temperatures up. In the same way, if a pocket of cold air comes in it will lead to a loss of energy.

A depression is formed when you’ve got warm air rising slowly over colder air at the warm front, theres a warm sector inbetween the warm front and the cold front, the cold front is formed where cold air is undercutting the warm air of the warm sector causing it to rise. ( you’ll need to know the weather conditions for this as well!)

The adiabatic lapse rate, is the rate at which air cools when it rises. Its about 10 degrees per km.

Im on OCR as well so if you need any help feel free to p.m or email, whatever.

The exams is on Friday.... * deep breath *....

Reply 2

Don_MESS

Im doing OCR too. What are the human activities effecting the heat energy budget?

Reply 3

meawinner1

OOh i remember doing that question last year i think its the pollution stuff if you have the book that goes with the course its the los Angeles case study in the human section. Also talk about the urban heat island. You can talk about inversion layers caused by pollution and factories. I can't remember much more sorry hope it helps. :smile:

Reply 4

Don_MESS

ill have a look thanks..

Reply 5

Sleep

Los Angeles is a study for human environmental impact in a MEDC, there is VERY little to use for physical, ignore it.

1. What is Sensible Heat Transfer?
As the other person said... except can also be by water. Transfer via conduction as warm air / a warm ocean current moves into an area, transferring heat to it.

2. How is a Depression Formed?
A kink in the polar front allows warm tropical maritime air to push north into colder polar maritime air over the North Atlantic. This creates a warm front (warm TM pushing into cold PM). Behind this kink, cold PM pushes into the warm TM (as the PM behind moves at a faster rate) creating a cold front (where PM pushes into TM). As the warmer less dense TM air rises above the cold PM air, low pressure is created.

"and 3. What is the Adiabatic Lapse Rates all about?"
Not required anymore at AS. All you need to know is temperatures usually get colder with height, but at a temp. inversion may go up with height for a short while.

Human impact on local energy budgets: this has come up something like 5 times in the last 7 years looking at the case study questions, always almost identical question, you need to learn it.

Humans create reservoirs. These act a moderating influence. As they cool up and heat up less quickly than the land (due to convection currents), they cause lower temperatures in the day-time when they absorb heat and higher temperatures at night as they release it. This means at night temperatures are less likely to fall below 0degrees so ground and air frost are less likely to form. However, the air nearby will be more humid so the dew-point is lower so fog and mist are more likely to form.

Humans put greenhouses and plastic sheets around crops. These reflect outgoing long-wave radiation, so there is less energy loss, so there is less radiative cooling. They also seperate the area from the colder surrondings. This means temperatures around the crops do not drop as low making frost less likely to form.
Humans spray crops as they approach freezing. As temperatures drops, humans can spray crops with water. As the temperature drops to 0degrees this water freezes around the crops. As the water freezes, it releases heat (latent head of condensation) which will help prevent temperatures falling any further. This works because most crops do not usually get fatally damaged unless their temperature falls below -2degrees.

Urban areas have an effect. Urban areas are hotter due to central heating etc. This means at night temperatures are far less likely to fall below 0degrees. This means that frost is less likely to form, and the air is less likely to reach dew point so dew, mist and fog are less likely to form.

Humans salt/grit roads making frost less likely to form.

Much more detail possible than I put on urban areas. But, strictly speaking, just mentioning 2 clearly and properly explained examples is enough to get you 10/10. I usually plump for 3 or 4 and explain them concisely but properly, as that means you are more likely to get the marks. If you learn some bits like I have u dont need to learn other bits like the effects of urban areas with wind tunnels and large scale convection and pollution etc. etc.

Reply 6

Don_MESS

You seem 2 know yr stuff. thanks a lot. What are the human impacts on making mass movements accelerate? n how do u stabilise them?

Reply 7

Sleep

Humans build on top of slopes. This destabilises them and accelerates rotational slumping (e.g. Walton-on-the-Naze UK- a pillbox built on top of the slope in WW2 is now on the beach at the bottom of it).
Humans deforest slopes. Vegetataion stabilises slopes and slows mass-movement: its roots bind soil together preventing soil creep and solifluction, and it intercepts/absorbs water so earthflows/soil creep/solifluction which all use water are less likely/slower. Humans stabilise slopes with afforestation, accelerate mass movement by destabilising them. Vegetation is removed for timber, by grazing animals or by trampling tourists.
Humans mine and quarry in slopes. This can destabilise them and cause collapse: mining caused part of Turtle rock mountain, Canada to collapse in 1903 killing 76.
At Vaiont Dam, in Italy, the water level in the valley behind the dam was increased by its construction. This meant that areas of the slope already undercut by water were undercut even more by increased water pressure and more of the slope was undercut by water. This accelerated soilcreep; occuring at up to 40cm a day before the disaster. It also lubricated a 2x1.5x1 km piece of rock, which fell down the slope in a landstream, causing a wave that engulfed a nearby village in 1963 killing I forget how many.
At Aberfan in North Wales humans caused a rapid Earth-flow. A slag heap was placed on top of a slope there. There were many springs there due to the porous local sandstone. This caused water to build up under the slag heaps. Aided by rapid rainfall, the water lubricated the heap to such an extent that part of it broke off, sliding downhill rapidly under the influence of gravity engulfing a local primary school killing 144, mostly children.
Humans can therefore accelerate mass movements in various ways in various locations.

They can stabilise slopes through afforestation, placing mesh to prevent soil-creep and bind the soil together, using signs/duck boards to direct tourists so the areas in which they kill vegetation are more limited, cliff-foot strategies (where slopes are eroded at their base by the coast- eg rip-rap boulders.
For a 4-6 mark question, you should choose 2 of these (different ones: best ones to plop for are mesh and afforestation) and explain them properly.
For a 4-6 mark question, a list wont do.

No problem, practicing these very common questions helps me as much if not more than you :smile:

Reply 8

Don_MESS

thanks again. really helpful. good luck wid exam 2moz, i hope i get the questions i want. lol.

Reply 9

TheWolf

Good luck guys :smile:

Reply 10

Don_MESS

how did u find it? i thought physical was tricky but other 2 =easy. But hard 2 tell.

Reply 11

Sleep

I thought physical was harder than usual but still not too bad. Investigation was quite simple but probably harder than usual to get really good marks in it, plenty of places I can see to penalise people. Human I thought was reasnobly hard compared to usual, there was much more application and a lot of the four and six markers seemed to be explain ones which were level marked, so prolly harder to get 100% from those.