Hi there, I'm wondering if anyone can tell me what direction the prevailing winds are in Canberra, and what the optimal window positioning would be to capture cooling winds and achieve good cross-ventilation? Many thanks!
Optimal window positioning for cross-ventilation in Canberra
(7 posts) (4 voices)-
Hi DK
In open country around the north of the ACT winds are either east-south-east or west-north-west.There is a useful web page that shows the pattern of wind flow every three hours. It has enough detail to show what you want, I think.
https://earth.nullschool.net/#2014/01/09/0300Z/wind/isobaric/1000hPa/orthographic=-216.30,-31.96,3000You will see a map, probably of south-east Australia, with flow-lines of the wind streaming across it.
Click the label "Earth" in the lower left corner to see the legend.
To get the wind pattern at the current time, Click "Control/Now".
Make sure you don't have the wind pattern for the stratosphere by clicking "Height/Sfc"
You need to place Canberra on the map. Canberra is about 35.3 degrees South, 149.1 degrees East. Click on the point on the map where you think it is. A panel appears above the main legend giving the Latitude, Longitude, and wind of that point. Find the correct location of Canberra by trial and error.
You can advance the time shown by hitting a little single arrow-head in the legend line headed "Control".
Date and Time are shown in the top line of the Legend.You were asking for more general information, but you can work out the generalities when you practice using these winds for specific times.
Locally, the winds will tend to follow the valleys.
Posted Sunday 17 Dec 2017 @ 6:05:56 am from IP # -
arttt
MemberTonight is a good example of the sort of breeze you want to capture in a Canberra summer.
http://www.bom.gov.au/products/IDN60903/IDN60903.94926.shtml
You will see at about 5:30 it swung around to come from the east, strengthened and the temp dropped away quickly. This is quite a regular canberra summer thing, but not every day. I understand this is a sea breeze that comes late in the day as we are quite a way from the coast.The northerlies and westerlies are generally hot and not worth opening the house up to catch.
There are lots of variables in getting cross ventilation right. In my place i only have a couple of small eastern windows but that is enough for the cool easterly breeze as it tends to get cool quickly, stay cool all night and is a strong breeze.
The critical times for ventilation in my place are when there is no breeze and it stays hotter outside then inside until somewhere after 1am. We open up when we get up in the morning and ideally want maximum air flow through the house before the day heats up from about 8am. Its a short space of time to cool the thermal mass down a bit. Big openings and stack effect help in our case.
Posted Sunday 17 Dec 2017 @ 10:46:34 am from IP # -
The summer evening easterly that arttt describes behaves rather like a sea breeze, but it is a pseudo-sea breeze.
It does not begin at the sea-shore. It begins at the great escarpment of NSW, which is just east of Braidwood. In summer, the air near the ground gets just as hot on the east and west sides of the escarpment. But the ground is about 600 metres (2000 ft) higher on the western side.
As a result, the air at about 1000 metres above sea level over the escarpment has two quite different temperatures: the air on the east is several degrees colder than the air on the west. About noon, the boundary between the two masses of air collapses, with the cold coastal air rushing inland under the warmer inland air.
The layer of cold coastal air is still several hundred metres thick as it flows over Canberra. Late in the evening the front of the cold air mass can reach as far as Harden. By then it is very shallow.Yes, I agree, although westerly winds are common in Canberra, they are not much use for cooling.
Posted Monday 18 Dec 2017 @ 5:57:36 am from IP # -
Ben1
MemberI would also add that my Canberra casement windows were installed to open out to the east to help catch the summer easterlies. It works brilliantly compared to sliding or awning windows where the wind can blow past parallel to the opening.
In winter, it is of no significance as the windows are closed for 7 months of the year.
Posted Tuesday 26 Dec 2017 @ 10:07:35 am from IP #
