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## What are the circulation pattern cells in the earth's atmosphere near the equator?

James J.
Featured 6 months ago

#### Explanation:

I believe you are referring to Hadley cells.

The diagram above shows all the circulation cells of the atmosphere, and you can see the ones just north and south of the Equator are called Hadley cells (named after George Hadley who first describe the mechanisms for trade winds).

At the equator the high amount of solar energy heats the atmosphere. There is a lot of moisture at the equator (there is a lot of ocean at the equator), and that adds water vapor to the atmosphere. Water vapor has a lower weight than nitrogen (the primary component of the atmosphere) and that lowers the weight of the atmosphere and therefore the pressure. Furthermore, as the air is heated it expands and that lowers the density causing upward motion of air. End result the air is rising.

As the pressure decreases with height the temperature decreases as well. This lowers the amount of water vapor the air can hold and cause precipitation. This is important later.

With lower pressure at the equator, the pressure gradient force (force causing air to move from areas of high pressure to areas of low pressure) brings air to the Intertropical Convergence Zone (named due to the incoming air converging). End result of this is surface winds move air toward the equator.

With air converging and rising at the equator, when it reaches the tropopause (top of the troposphere) it is forced to move outward away from the equator. As it moves further away, and as has further precipitation the weight of the air increases. This causes descending motion of air at around 30 degrees latitude. This air, as it descends also warms from the increase in pressure. This further dries out the air and increases pressure. This is why if you look around the globe you will see a lot of deserts at around 30 degrees latitude.

As you can see from the global diagram above this closes the system, giving you your Hadley cell.

## What's the difference between geologic column and geologic time scale?

Geoearth
Featured 6 months ago

One looks at types of rocks and their age, the other is just age

#### Explanation:

A geologic column (Stratigraphic column) is a representation of where different rocks sit relative to each other. A Strat column (for short) shows characteristic features of these rocks and can display their age. It is a good way to understand the geological sequence of an area.

A geological timescale is simply a scale that puts Earth's history into different eras, epochs and ages. Each section has an age attached to it, so you can look at it and say "500 million years ago, the Earth was in the Cambrian period". This time scale is being constantly updated as measuring the age of rocks becomes more precise. Here is the latest version:

## What do you call the lines on a topographic map that indicate the elevation of the land forms?

Eder Guedes
Featured 5 months ago

They are called "contour lines".

#### Explanation:

The contour lines are used to indicate the elevation on topografic maps. Usually, we use two types of lines to represent the landforms in a map. The regular line and the master line. The master lines, or master contours, are used to indicate, graphically, the elevation of the seccion of the relief, and they are represented in a different color on the map.

For example, in the map, below the contour lines are represented in red, and the master contours are represented in green.

## How do scientists measure the porosity of soil?

Ms. Worth
Featured 2 months ago

You can find the porosity of soil by measuring the amount of water it takes to fill all the tiny pores in the soil.

#### Explanation:

The porosity of soil is the volume of space in between the mineral particles of soil. Porosity varies greatly from one kind of soil to another because the grains of soil are loosely or densely packed.

Here's an image of different kinds of soil with different porosities:

To calculate the porosity of a soil sample, determine the volume of the empty spaces between particles by seeing how much water it takes to fill all those little pores.

Here is one method to find the porosity of soil.

Calculating Porosity Experimentally by $\text{Saturation}$

1) Gently dig up a sample of the soil you want to measure.
Don't be rough with the sample because handling it too much may disturb the structure of the soil.

2) Transfer the soil sample to a graduated beaker to measure the volume of the soil. Record this volume exactly.
This measurement is the $\text{Volume of the Sample}$ ${V}_{s}$

3) Measure out a generous amount of water into a graduated cylinder. Start with more water than you will need. Record this volume exactly.

4) Saturate the soil sample with the water. Get the water as close as you can to the exact top of the soil in the beaker -- but don't go over the top

5) Subtract the volume of water that you used up from the starting volume in the graduated cylinder. That shows you how much water it took to saturate the soil.

6) The volume of the water used is equal to the Pore Volume ${V}_{p}$

$\text{Porosity}$ = $\left(\text{Pore Volume")/("Total Volume}\right)$ $\times$100%

7) You find "Total Volume" by adding ${V}_{s} + {V}_{p}$

8) So you can use a scientific calculator to come up with this number by doing this math:

$\text{Porosity}$ $=$ $\left(\text{Pore Volume") / ("Sample Volume + Pore Volume}\right)$ $\times$ 100%

9) This is the formula for this calculation

P_t= (V_p )/ (V_s +V_p) xx 100%

Here's a WikiHow article that describes other ways to calculate soil porosity:
https://www.wikihow.com/Calculate-Porosity

## Why do clouds usually form at the leading edge a cold air mass?

James J.
Featured 2 months ago

Cold air pushes warm air aloft.

#### Explanation:

As cold air is more dense than warm air, the leading edge of a cold air mass works like a plow, pushing warm air upward.

https://aesnotes.wordpress.com/2013/07/08/fronts/

As with any rising air the temperature will drop due to a drop in pressure as per Gay-Lussac's law. As the temperature drops the relative humidity increases since the amount of water vapor the air can hold is based on the temperature of the air.

https://goldsealnews.wordpress.com/2012/03/20/measuring-humidity-in-your-home/

So if the rising air is 20 degrees and at 50% relative humidity, the number of grams per kilogram of air (absolute humidity) will remain the same but when the air cools to 10 degrees it will then be about 100% relative humidity. At 100 % relative humidity the water vapor will begin to condense forming clouds.

## Which part or Australia typically receives the most moisture?

Ms. Worth
Featured 2 months ago

The part of Australia with the most precipitation is the Tropical Climate area in the north

#### Explanation:

Rainfall in Australia tends to decrease as you move from north to south, and as you move from the east coast to the interior.

So the areas of high rainfall tend to generally occur in a curve from the north of the continent, then around to the east side, then down to the south.

Here is a color-coded map that shows the average yearly precipitation in Australia:

According to the web site "Climates to Travel,"
https://www.climatestotravel.com/climate/australia
the precipitation of Australia can be conveniently divided into four large regions:

1. Tropical climate (Darwin, Brisbane) --The rainiest area

3. Arid climate
4. South-east (Canberra, Sydney, Melbourne, Hobart)
$\textcolor{w h i t e}{m m m m m m m m}$_____

1. The Tropical Climate area

The vast northern area has a tropical climate, with a dry and sunny season ("the dry"), usually from May to October, and a rainy and muggy season ("the wet"), usually from November to April.

The annual rainfall exceeds 15.5" and is more abundant along the northernmost and the eastern coasts, where it exceeds 47".

The tropical rains occur mainly in the afternoon or evening in the form of downpours or thunderstorms. In the south-east, where Brisbane is located, the winter is cooler, so the climate becomes sub-tropical. Vegetation is savanna-type in the driest areas, with rainforests in the wettest part of the north-eastern coast.

In Darwin, the capital of the Northern Territory, 58.5" of rain per year fall, mostly between November to early April. The rainiest month is January, with almost 15.5" of rain. But from May to September it almost never rains.

Here is the average precipitation in inches for Darwin:

Jan|Feb|Mar|Apr|May|Jun|Jul|Aug|Sep|Oct|Nov|Dec|  YEAR
———————————————————————————
15 | 12 | 10 |  4  |  tr  | tr  | 0 |  0   |  tr  |  2  |   5  | 10 |    58.5

Here is a map of the Tropical Climate area

$\textcolor{w h i t e}{m m m m m m m m}$_____

2. The Mediterranean Climate
There are a couple of areas with a Mediterranean climate, with mild and rainy winters, and warm and sunny summers.

In Perth, Western Australia, 31.5" of rain falls in a typical year, most of which occurs from May to August, with a maximum of 6.7" in July, the central month of winter.

Here's a map of the Mediterranean climate areas of Australia:

$\textcolor{w h i t e}{m m m m m m m m}$_____

3. The Arid Climate
In the vast area called "Outback", the climate is arid, semi-desert (where annual precipitation is between 8 and 16" per year), or even desert (below 8" per year.)

In the semi-desert area, the rains in the north-central part fall in the form of downpour or thunderstorm in the hottest period, while in the southernmost part they occur mostly in winter.

In the most arid area, the rains are rare and sporadic, but every now and then a thunderstorm may erupt, most likely in summer.

Here is a map of the Arid Climate area

You can find out more about Australia's climate here:
http://www.abs.gov.au/ausstats/[email protected]/Lookup/by%20Subject/1301.0~2012~Main%20Features~Australia%27s%20climate~143

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