The image above represents free air anomaly.

To compute for free air anomaly, four essential parameters are needed and these parameters are **Observed or Measured Gravity Value (g _{obs}), Reference Value of Gravity (g(λ)), Elevation (h) **and

**Radius of the Earth (R).**

The formula for calculating free air anomaly:

δg_{F} = g_{obs} – g(λ) [1 – ^{2h}/_{R}]

Where:

δg_{F} = Free Air Anomaly

g_{obs} = Observed or Measured Gravity Value

g(λ) = Reference Value of Gravity

h = Elevation

R = Radius of the Earth

Let’s solve an example;

Find the free air anomaly when the observed or measured gravity value is 9, reference value of gravity is 10, elevation is 16 and radius of the earth is 4.

This implies that;

g_{obs} = Observed or Measured Gravity Value = 9

g(λ) = Reference Value of Gravity = 10

h = Elevation = 16

R = Radius of the Earth = 4

δg_{F} = g_{obs} – g(λ) [1 – ^{2h}/_{R}]

δg_{F} = 9 – 10 [1 – ^{2(16)}/_{4}]

δg_{F} = 9 – 10 [1 – ^{32}/_{4}]

δg_{F} = 9 – 10 [1 – 8]

δg_{F} = 9 – 10 [-7]

δg_{F} = 9 – -70

δg_{F} = 79

Therefore, the **free air anomaly **is **79 Gal.**

Nickzom Calculator – **The Calculator Encyclopedia** is capable of calculating the free air anomaly.

To get the answer and workings of the free air anomaly using the **Nickzom Calculator – The Calculator Encyclopedia. **First, you need to obtain the app.

You can get this app via any of these means:

**Web** – https://www.nickzom.org/calculator-plus

To get access to the **professional **version via web, you need to **register** and **subscribe **for** NGN 2,000 **per** annum** to have utter access to all functionalities.

You can also try the **demo **version via https://www.nickzom.org/calculator

**Android (Paid)** – https://play.google.com/store/apps/details?id=org.nickzom.nickzomcalculator

**Android (Free)** – https://play.google.com/store/apps/details?id=com.nickzom.nickzomcalculator

**Apple (Paid)** – https://itunes.apple.com/us/app/nickzom-calculator/id1331162702?mt=8

Once, you have obtained the calculator encyclopedia app, proceed to the **Calculator Map, **then click on **Geology**** **under **Add-on****.**

Now, Click on **Gravity **under **Geology**

Now, Click on **Free Air Anomaly **under **Gravity**

The screenshot below displays the page or activity to enter your values, to get the answer for the free air anomaly according to the respective parameters which are the **Observed or Measured Gravity Value (g _{obs}), Reference Value of Gravity (g(λ)), Elevation (h) **and

**Radius of the Earth (R).**

Now, enter the values appropriately and accordingly for the parameters as required by the **Observed or Measured Gravity Value (g _{obs})** is

**9**,

**Reference Value of Gravity (g(λ))**is

**10**,

**Elevation (h)**is

**16**and

**Radius of the Earth (R)**is

**4**.

Finally, Click on Calculate

As you can see from the screenshot above, **Nickzom Calculator**– The Calculator Encyclopedia solves for the free air anomaly and presents the formula, workings and steps too.