Atmospheric Layers

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Questions and Answers

What is the altitude range of the Mesosphere?

11 ≤ H ≤ 47 km

84.9 km ≤ H

0 ≤ H ≤ 11 km

47 ≤ H ≤ 84.9 km (correct)

Where is most of the ultraviolet light absorbed?

At the ground

Near the stratopause (correct)

In the atmospheric boundary layer

In the thermosphere

What is the approximate height of the tropopause near the Earth's poles?

11 km

18 km

8 km (correct)

47 km

Which layer of the atmosphere is often turbulent?

Atmospheric Boundary Layer Signup and view all the answers

What is the primary factor that slows down the wind in the atmospheric boundary layer?

Surface drag Signup and view all the answers

What is the altitude range of the Troposphere?

0 ≤ H ≤ 11 km Signup and view all the answers

What happens to the air in the atmospheric boundary layer during daytime?

It warms Signup and view all the answers

What is the average height of the tropopause in mid-latitudes?

11 km Signup and view all the answers

Where do almost all clouds and weather occur?

Troposphere Signup and view all the answers

Why did railroad companies create standard time zones in the 1800s?

To publish and maintain precise schedules Signup and view all the answers

How many degrees of longitude does one hour of elapsed time span?

15° Signup and view all the answers

What is the purpose of Coordinated Universal Time (UTC)?

To provide a unified global time standard for meteorology Signup and view all the answers

What is the time zone designation for the zone that is 1 hour ahead of Greenwich Mean Time?

A Signup and view all the answers

What is the name of the time zone that spans 7.5° on each side of the prime meridian?

UTC time zone Signup and view all the answers

What is the local time of day in time zones east of the UTC zone?

Later than at Greenwich Signup and view all the answers

What is the time zone designation for the zone that is 1 hour behind Greenwich Mean Time?

N Signup and view all the answers

Why are time-zone boundaries sometimes modified?

To enhance commerce and follow political or geographic boundaries Signup and view all the answers

What is the name of the time zone that is used in most of western Europe?

All of the above Signup and view all the answers

How many time zones are there in North America?

8 Signup and view all the answers

Study Notes

Layers of the Atmosphere

The atmosphere is divided into four layers based on temperature structure: Thermosphere, Mesosphere, Stratosphere, and Troposphere.
The height of each layer is defined as:
- Thermosphere: 84.9 km ≤ H
- Mesosphere: 47 km ≤ H ≤ 84.9 km
- Stratosphere: 11 km ≤ H ≤ 47 km
- Troposphere: 0 km ≤ H ≤ 11 km
Almost all clouds and weather occur in the Troposphere.

Boundaries of the Layers

The top limits of the bottom three layers are named:
- Mesopause: H = 84.9 km
- Stratopause: H = 47 km
- Tropopause: H = 11 km
The Tropopause height varies with latitude:
- Lower (around 8 km) near the Earth's poles
- Higher (around 18 km) near the equator
- Average height in mid-latitudes: around 11 km, with seasonal variations (lower in winter, higher in summer)

Temperature Maxima

Three relative maxima of temperature occur in the atmosphere due to absorption of solar radiation:
- Ultraviolet light absorption by ozone near the Stratopause
- Visible light absorption at the ground
- Absorption of most other radiation in the Thermosphere

Atmospheric Boundary Layer (ABL)

The bottom 0.3 to 3 km of the Troposphere is called the Atmospheric Boundary Layer (ABL)
The ABL is often turbulent and varies in thickness in space and time
It is affected by the Earth's surface, which:
- Slows the wind due to surface drag
- Warms the air during daytime and cools it at night
- Changes in moisture and pollutant concentration
Most of human life is spent in the ABL

Time Zones

Each town had its own local time before the 1800s, with noon being when the sun was highest in the sky.
Railroad companies created standard time zones in the 1800s to enable precise schedules, and it was eventually adopted worldwide.

Calculating Time Zones

The Earth makes one complete revolution in one day, covering 360° of longitude.
Each hour of elapsed time spans 15° of longitude, resulting in each time zone spanning approximately 15° of longitude.
This means neighboring time zones are usually 1 hour different from each other.

Time Zone Characteristics

All clocks within a time zone are set to the same time.
Time-zone boundaries are sometimes modified to follow political or geographic boundaries for commercial purposes.

Coordinated Universal Time (UTC)

UTC is the time zone at the prime meridian, also known as Greenwich Mean Time (GMT) and Zulu time (Z).
The prime meridian is in the middle of the UTC time zone, spreading 7.5° on each side.
UTC is the official time used in meteorology for coordinating simultaneous weather observations worldwide.

International Time Zones

Time zones are designated by letters A-Z, with Z being at Greenwich.
East of the UTC zone, local time zones (A, B, C, ...) are ahead of Greenwich time, while west of the UTC zone, local time zones (N, O, P, ...) are behind.
Each zone can have multiple local names, depending on the countries it spans.

Examples of Time Zones

Most of western Europe is in the Alpha (A) zone, also known as Central Europe Time (CET) or Middle European Time (MET).
North America has 8 time zones, designated by letters P to W.

International Date Line

The international date line is near 180° longitude in the middle of the Pacific Ocean.
When traveling east to west across the date line, you lose a day, while traveling west to east, you gain a day.

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Description

Learn about the different layers of the atmosphere, including the troposphere, stratosphere, mesosphere, and thermosphere, and their characteristics based on temperature structure.