Wind & Heat

Weather is.... The current state of the atmosphere...what is happening right now

Weather Factors Weather: The state of the atmosphere at a specific time and place Convection: transfer of heat in liquids and gas. Moves heat through atmosphere and ocean. TEMPERATURE= the average motion of molecules ↑ TEMP= ↑movement of molecules= feels hot ↓ TEMP= ↓movement of molecules= feels cold

Convection Currents Warm air= expanding or rising air= leaves behind L pressure Cold Air=sinking air= leaves an area of H pressure

Wind Movement Uneven heating of the earth’s surface causes some areas to be warmer than others. As we know, warm always follows cold to share it’s warmth- when this happens in the atmosphere, wind happens Equator- warm Poles- cold

Wind Basics Winds are measured by direction and speed Wind is caused by a difference in air pressure. Air pressure changes because of an uneven heating of the atmosphere. Winds are measured by direction and speed The anemometer is the tool we use to measure this Wind chill=↑ cooling the wind causes

Local Winds: occur over small area The land cools and heats faster than the ocean. Water holds heat longer than land, and takes longer to heat or cool. SEA BREEZE During the day, the land gets hotter faster than the water. The heated air rises & molecules spread out, leaving behind an area of low pressure. Wind from the cooler sea blows in to take the place of that warmer air. These happen during the day!

Land Breezes At night the lands cools off faster than the sea. Cool air sinks creating an area of high pressure. Wind blows from the land to the sea.

Pressure Gradient When land is hotter than water, the heat rises and wind from the sea replaces the warm air. This creates a pressure gradient. From sea to land, the wind moves from high pressure to low pressure. The lower the pressure, the higher the gradient. Wind speed depends on the gradient. High gradient= strong winds low gradient= weak winds The force that provides the strength for wind to blow is the pressure-gradient force.

Global Winds: over large area Wind belts: Horse Latitudes= 30°N and S of equator =calm winds- area of falling air Jet Streams= 10km (upper troposphere) blow from the west to the east. Narrow zone of strong winds.

Global Winds cont. Tradewinds: Easterly winds that blow from horse latitudes to the equator.

Global Winds cont. THE DOLDRUMS... is the area around the equator where there is little to no wind. These calm areas have rising air.

Coriolis Coriolis Effect: the way Earth makes winds blow in a curved manner because of rotation (right to left rather than up or down) Causes winds to blow towards the right in the northern hemisphere and to the left in the southern hemisphere. Responsible for rotation in hurricanes.

Heat Transfer Conduction: the direct transfer of thermal energy (heat) from one substance to another substance that is touching. Radiation – the direct transfer of thermal energy (heat) by electromagnetic waves. Convection: the transfer of thermal energy (heat) by the movement of a fluid.