Weather and Climate

Meteorology The study of the atmosphere The study of the atmosphere –Rain, dust, haze, smoke, lightening-- the weather

Weather The current state of the atmosphere The current state of the atmosphere What is going on right now What is going on right now

Climate Long-term variations of weather Long-term variations of weather Average over many years Average over many years

Why is there different climates and seasons? Earth is tilted therefor the sun hits the earth at different angles Earth is tilted therefor the sun hits the earth at different angles The straighter the angle, the warmer the heat The straighter the angle, the warmer the heat ** Earth distributes the heat throughout the globe ** Earth distributes the heat throughout the globe

Coriolis Effect Because of the rotation of earth perfect convection currents don’t occur. Because of the rotation of earth perfect convection currents don’t occur. Particles move to the right in the north and the left in the south Particles move to the right in the north and the left in the south

The coriolis effect combines with the heat imbalance to create a global wind system The coriolis effect combines with the heat imbalance to create a global wind system

Air mass A body of air that takes on the characteristic of the area it forms A body of air that takes on the characteristic of the area it forms With the movement of the Earth and convection the air mass moves and exchanges heat with the new area it is over. With the movement of the Earth and convection the air mass moves and exchanges heat with the new area it is over.

Global Wind System Caused by 3 different convection cells Caused by 3 different convection cells 3 basic wind systems 3 basic wind systems –1. Trade winds –2. Prevailing Westerlies –3. Polar Easterlies

Trade Winds Occur at the 30o N and S Occur at the 30o N and S Air cools and sinks here and moves to the equator where it is warmed and rises again Air cools and sinks here and moves to the equator where it is warmed and rises again

Result of the Trade winds The rising air from the trade winds migrate either north or south based on the season The rising air from the trade winds migrate either north or south based on the season Causes cloudiness and showers that provide the rain for the rain forests Causes cloudiness and showers that provide the rain for the rain forests

Prevailing Westerlies Flows between 30o and 60o N and S Flows between 30o and 60o N and S Circulate opposite the trade winds Circulate opposite the trade winds Responsible for most the weather in the United States and Canada Responsible for most the weather in the United States and Canada

Polar Easterlies Lies between 60o and the poles Lies between 60o and the poles Brings cold air to the larger continents Brings cold air to the larger continents

Jet Streams Earth’s weather is influenced by atmospheric conditions and events that occur at the boundaries between wind zones Earth’s weather is influenced by atmospheric conditions and events that occur at the boundaries between wind zones

Winds Cont Surface and upper air differ greatly in temperature and pressure Surface and upper air differ greatly in temperature and pressure

Jet Streams cont. Narrow bands of fast, high-altitude, westerly winds Narrow bands of fast, high-altitude, westerly winds Located where the wind systems meet (between the polar easterlies and prevailing westerlies) Located where the wind systems meet (between the polar easterlies and prevailing westerlies)

Fronts The narrow region separating two air masses of different densities (caused by different pressures or temperatures) The narrow region separating two air masses of different densities (caused by different pressures or temperatures)

4 types of Fronts 1. Cold Fronts 1. Cold Fronts 2. Warm Fronts 2. Warm Fronts 3. Stationary Fronts 3. Stationary Fronts 4. Occluded Fronts 4. Occluded Fronts

Cold Fronts Forces warm air up and causes clouds, showers, and thunderstorms Forces warm air up and causes clouds, showers, and thunderstorms On a weather map represented as blue line with blue triangles point in the direction of movement On a weather map represented as blue line with blue triangles point in the direction of movement

Warm Front Extensive Cloudiness and precipitation Extensive Cloudiness and precipitation –June Gloom Represented by a solid red line with solid red semi-circles Represented by a solid red line with solid red semi-circles

Stationary Front Meeting of two mild fronts Meeting of two mild fronts No heavy weather No heavy weather Represented by a combination of red circles and blue triangles Represented by a combination of red circles and blue triangles

Occluded Front When two cold air masses which force a warm air mass upwards When two cold air masses which force a warm air mass upwards Strong winds and heavy precipitation Strong winds and heavy precipitation

Pressure zones High pressure- Associated with fair weather High pressure- Associated with fair weather Low pressure-- clouds and precipitation Low pressure-- clouds and precipitation

When no front is over the area, the weather is like the air mass sitting on top