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Meterology.

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by

Mariama Ceesay

on 17 May 2011

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Transcript of Meterology.

Meteorology - Branch of the natural sciences that deals with the Earth’s atmosphere & its related phenomena 4 Factors that Cause Weather:

* Temperature
* Air Pressure
* Wind
* Moisture Meteorology :) Earth’s Atmosphere:

79% Nitrogen

20% Oxygen

1% Everything Else

Variable Components

* Water Vapor
* Aerosols--suspended solid & liquid particles in the atmosphere
* Ozone--(O3) absorbs harmful UV radiation & damaged by CFC’s. Thermosphere-- fourth layer

* Ionosphere-lower thermosphere, made of

charged ions.


* Exosphere-upper thermosphere, satellites orbit at this location.


* Van Allen Radiation Belts-layers of high radiation that help block solar particles. Unequal Heating of the Earth

* 1. Direct Sunlight Energy (comes at a 90º angle) causes more HEAT. It occurs most often at the equator.


* 2. Indirect Sunlight Energy (comes in at an angle less than 90º) doesn’t produce as much heat. Heat Transfer.
Radiation

* Sun gives off light energy because of nuclear fusion. (Fusing of 2 hydrogen atoms into a single helium atom)

* Atmosphere absorbs most of the radiation.

* Ground absorbs the rest. Conduction--the direct transfer of heat energy from one substance to another.

**The warmth of the Earth’s surface slightly warms the air that it comes in contact with. Convection--the transfer of heat energy in a gas or liquid

**Warm air rises, cold air sinks “Greenhouse Effect”-- CO2 collects in the atmosphere & traps heat energy at the surface. (CO2 is 0.036%) Air Pressure

Air has mass, so its weight (gravity) pushes down on the earth causing pressure.


Movement of Air:

1. Warm air expands, making it less dense so it rises causing LOW pressure. Warm air holds more moisture. Air has mass, so its weight (gravity) pushes down on the earth causing pressure.


B. Movement of Air

1. Warm air expands, making it less dense so it rises causing LOW pressure. Warm air holds more moisture. HIGH Pressure is usually associated w/ good/fair weather. Barometer (Mercury or Aneroid) measures the change in air pressure in either millibars or millimeters/inches of mercury. Wind

Definition: the movement of air from one place to another


Air moves from an HIGH pressure to LOW pressure. Global Winds

* Created by the unequal heating of the Earth’s surface, difference in air pressure& the Earth’s rotation.


Coriolis Effect--due to the Earth’s rotation, moving objects such as air and water will shift in a certain direction. Global Wind Belts

* Trade Winds – winds that blow from east to west on either side of the equator. Separated by the Doldrums
*

* Prevailing Westerlies – winds that blow from west to east between 30o & 60o north & south latitudes.
*

* Polar Easterlies - winds that blow from east to west in the polar regions. Jet Stream

* A narrow stream of high pressure wind found in the lower stratosphere.


* Pushes large air masses across the globe. Measuring Wind

1. Wind Speed--Anemometer


2. Wind Direction--Wind Vane


Measured in mi/hr, km/hr,

and knots. Moisture

A. Humidity

1. The measure of the amount of water vapor in the atmosphere. 1. Specific Humidity--measure of the actual mass of water vapor in a given mass of air.



1. Relative Humidity--ratio/percentage of the actual amount of water vapor in a given mass of air compared to the maximum amount of water vapor that air can hold at a given temperature. * Psychrometer--a type of hygrometer that has a wet bulb thermometer & a dry bulb thermometer


* Dew Point Temperature--the temperature to which air has to be cooled in order to be completely saturated (filled) with water. Clouds

* Suspended droplets of water that collect on aerosols.


* Formation of clouds depend on the amount of moisture & aerosols in the air, the air temperature, & the stability of the air (air pressure.) Cirrus – high clouds that are thin & wispy. Made of ice crystals.



Stratus – low level clouds that have a layered look. Cumulus – large, fluffy clouds of vertical development.

The prefix alto- is added to the name of clouds formed in the middle cloud layer. The prefix/suffix nimbus- is added to the name of a cloud that produces precipitation Precipitation

1. Rain

2. Hailstones

* Form in cumulonimbus clouds
* Strong winds carry rain drops above the freezing line.
* Rain drops freeze into ice pellets & fall.
* Stronger the wind, the larger the hailstone Sleet

* Rain freezes into an ice pellet as it falls through a pocket of freezing air.



4. Freezing Rain

* Rain falls to the ground and freezes on contact with the surface Snow

This occurs when cloud droplets freeze in the clouds and stick together forming flakes. Air Masses

1. Definition: a large body of air that is the SAME throughout
2. Types

**Named based on where the air formed, its temperature, and its humidity 1. Maritime Polar--it forms over the Northern Atlantic and Pacific Oceans.

*Brings COLD, MOIST air


1. Maritime Tropical--it forms near the equator. It brings WARM, MOIST air.

*If it comes in contact with cooler air from the North, storms will form. 1. Continental Polar--it forms over northern Canada. It brings COLD, DRY air.

*Causes extremely cold temperatures in the United States.


4. Continental Tropical--it forms over land in Mexico. It brings HOT, DRY air. Fronts

* The boundary where two air masses collide.


* The front is named for the aggressive air mass. Cold Front

Cold air meets and replaces a mass of warm air.


* Fast in speed.
* Form cumulus clouds.
* Narrow frontal zone
* Short, severe weather Warm Front:
Warm air mass overtakes and moves over a cold air mass.
* Slow moving
* Forms stratus clouds
* Wide frontal zone
* Long periods of drizzle
* Overcast skies Stationary Front--neither air mass moves

* No bad weather




Occluded Front--a cold front catches up with a warm front and overtakes it

* Weather can be variable and the conditions can change. Dry Line

Dry air invades moist air.


* Fast moving
* Narrow frontal zone
* Forms cumulus clouds
* Severe weather in most cases Severe Weather

* Weather that can be considered life threatening and can cause damage to buildings
* Includes thunderstorms, lightning, tornadoes, flooding, hurricanes, etc. Watches and Warnings

Watches – a watch is issued when the conditions for a certain type of severe weather are possible, but not necessarily occurring at the moment.

Warnings – a warning is issued in a specific area where a type of severe weather is occurring at that given moment. Thunderstorms

* Fast moving rainstorms that can produce strong winds, hail, heavy rainfall, lightning & tornadoes.


1. Lightning – static electricity caused by the separation of electrical charges by the collisions of rain drops & strong winds. The positive & negative charges seek each other out. When they connect, an electrical discharge occurs creating a lightning bolt Thunder – the heat generated by the lightning bolt superheats the surrounding air causing it to expand so rapidly that it causes a sonic boom. Tornadoes

* Funnels of high speed circulating winds
* High winds & updrafts collide creating a circulating low pressure.
* The cloud begins to lower below the cloud base (wall cloud.) The low pressure extends to the ground picking up dust & debris forming a tornado. Hurricanes

* Tropical cyclone that has a low pressure center (eye) with several rotating thunderstorms & strong winds around it.
* Start as tropical depressions over warm water in the oceans. Storm builds strength as it travels over the warm water Flooding

* Kills more people in the U.S. than any other type of severe weather.
* Caused by too much rain over an extended period of time. It causes lakes, streams, rivers, etc. to overflow. Flash Flooding

* Flooding that mainly occurs in towns or cities.
* A rainstorm that dumps several inches of rain over a short period of time causes it.
* It is too much for the ground to soak up.
* It causes low lying areas to overflow and rushing water in other areas. SPECIAL THANKS TO MR. PORTER FOR HELPING ME WITH HIS NOTES! :)
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