Non rotating planet

Rotating planet

Wind belts: symmetric case, and then land effects

Angular momentum

Cha

nge

in le

ngth

of

day

(10-3

s)

time

• Length of the day varies by milliseconds due to climate

Dec/Jan/Feb

Wind as a functionof latitude and height

Jun/Jul/Aug

• Note the stronger jet in the winter hemisphere

Temperature as afunction of latitudeand height

Dec/Jan/Feb

Jun/Jul/Aug

Note the warmer summer hemisphere (duh)

Northern hemisphere winter (Dec Jan Feb) – Sea level pressure

Siberian High Aleutian Low

Icelandic Low

Northern hemisphere winter (Dec Jan Feb) – Surface wind

Note the approximate geostrophic balance (c.f. pattern of surf. pressure)

Northern hemisphere Winter circulation – pressure at 3km

What is the Geostrophic balance here?

Northern hemisphere Winter circulation

What is the Geostrophic balance here?

– pressure at 5.5km

Northern hemisphere Winter circulation

What is the Geostrophic balance here?

– pressure at 9.0km

Northern hemisphere - temperature difference from zonal average in lower troposphere. (0 to 5 km)

Heat flux from surface to atmosphere (Winter)

Wm-2

Cooling over land, heating over ocean (up to 4000W/m2 in a big storm)

Northern hemisphere winter (Dec Jan Feb) – Precipitation rate

Precipitation organized into storm tracks in Atlantic and Pacific basins

Storm tracks in the atmosphere

Density of tracks of storms in DJF, northern hemisphere

Southern hemisphere winter (Jun Jul Aug) – Sea level pressure

Pattern is much more zonal (east west) than Northern hemisphere

Southern hemisphere winter (Jun Jul Aug) – Surface wind

Note the approximate geostrophic balance (in southern hemisphere!)

Southern hemisphere winter circulation- pressure at 5.5km

What is the Geostrophic balance here?

Southern hemisphere: heat flux from surface to atmosphere (Winter)

Wm-2

Southern hemisphere winter precipitation (ish!)

What about the pattern here?

Storm tracks in the atmosphere

Density of tracks of storms in JJS, southern hemisphere

Distributions of storm are much more uniform