time zone - timestamp

Hello,

I created a table with:
"create table wrf (region integer, created_on timestamp(0) with time
zone, valid_for timestamp(0) with time zone, type varchar(5), max float,
min float, avg float, stddev float, var float);"

then i inserted data with:
"insert into wrf values ( $i, '2005-08-02 03:00:00 +00', now(), 'T2m',
(select max(tmp) from tmp_point where intersects(tmp_point.the_geom,
(select the_geom from regions where cat=$i))),.........."

then now I selected the columns created_on and valid_for:
"select created_on, valif_for from wrf;"

Result: 2005-08-02 05:00:00+02 | 2005-11-10 14:16:41+01

Now, my question:
Why time zone "+02" in "2005-08-02 05:00:00+02"? And why "+01" in
"2005-11-10 14:16:41+01"?
I think +01 depends on my system time. But why +02?

Greetings
Maik